basic field manual volume iii-1932

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BASIC FIELD MANUAL

Volume III

BASIC WEAPONS

PART THREE

MACHINE-GUN COMPANY

PREP ARED UNDER DIRECTION OF THU

CHIEF OF INFANTRY

1932

UNITED STATES

GOVERNMENT PRINTING OFFICE

WASJlINGTON : 1932

For lillIe by the Superintendent or I>ocuments. Washington, D. C.

'J'rlce'20 0011&8



OcnCTal.

OFFICIAL:

C. II. BRIDGES, ,J["jOT OenfTal,

Tile Adjutant

'VAR DEPARTMENT,

'VASIlI;\;OTON, June 10, 19,1.?

Part Three, Machine-gun COlllvany, Dasic ]'ipld ManulI'

Volume III,' Basic Wpallons, Is vuhlished for the informatIJl

and guidance of all concerned.

[A. G. 062.11 (4-13-31).] .'

By ORDER OF TIlE SECUE..'TARY O}' "~AU: ',•.

DOUGLAS MAcAHTIIUH, .

General,

Chlct of StulTr

Ii

Lf'

I

",'

•••



LIST OF FIELD MANUALS

A MANUAL FOR COMMANDERS OF LARGE UNITS. (M. C. L. U.)

Vol. I. O/lcratlon8.-A guide for commanders aod staffs for tactical

operations of large units.

II. Administratloro.-A guide for the administration of large units

in a theater of operations.

r' STAFF OFFICERS' FIELD MANUAL. (8 . O. F. M.)

Stal! prlnelpll's and functions appllcalJ1e to the statf~ of all units,

togl'ther with pertinent rl'ference data

BASIC FIELD MANUALS. (8. F. M.)

Training, admlnlHtrativ<', and reference data applicable to more than one

arm, with specllll reference to the smaller units

Vol. I. Fidel Service Pocketbook. (F. S. r.)-The individual.II. Infantrv Drill Regulations. (I. D. R.)-Drlll, dllmlOunted c('re-

monleM and inspections; the infantry pack, dlHplay of equip-

ment, and tent drlll.

III. Basio Weapon8. (n. W.)-Marksmanshlp and mechanical train-

ing of the rltle, automatic rltle, pilltol, machine gun, 37-mm.

gun, 3-lm'b trench mortar, bayonet, and grenade Instruction.

1'ecbnique of fire (37-mm. gun, 3-lnch trench mortar, and

D1l1cblne gUll) ; musketry and combat practice of small units;

inRtrumentfil.IV. Signal .Communlcatlon. (S. C.)-Signal regulation!! and tech-

nlc'al lnformatlclll Dl'f'dl'd by officers and enlisted men on

Hlgnal communlcatiolls duty of arms other than the Signal

CorpM. .

V. Transllort. (T.)-Ecjuitatlon, training remounts, ulle and carl"

of animals, anel of animal-drawn, pack, motor, and tractar

trllnHport.

VI. A,lmlMHtrative Regulation8. (A. R.)-Army Rc>gulatlons eBSen-

tllll to ",mall units.VII. Military IJaw. (1\1. L,)-The Manual for Courts-Martlal Includ-

Ing the Article's of War; the Rull's of Land Warfare, Includ-

ing rc'cent cOllvc'ntlons relative to the skk and wounded of

al'mll's In the field, and to prlHoners of war; an epitome of

the kglll pl'lnclpl"8 appllcable to mllltary forces when aiding

the ('Ivll powc'r.

VIII. Ollcratlon-s of Combfnr(J Arms (SmaU Unit8). (0. C. A.).-'J'he principles, duetrhH'8, Slid methods governing the tactical

rmp)oYllIcnt of combined arms with reference to the llmall,'" unIts.

III



(I. F. M.)nfantry Field Manual.

I V LIST OF }'JELD MANU AL1'l IFIELD MANUALS FOR THE ARMS

'.fbe manual for each arm contaIns, prImarily, the prInciple!:!, do<'trln

and metbods governIng the employment of that arm and pertln'reference data.

,Vol. I. Units other than Tanks.

II. Tank Units.

Cavalry Field Manual. (C. F. M.)

Field Artillery Field Manual. (F. A. F. M.)

Vol. I. Organization and Drill.

II. Tactics and Tech1/;ique.

Coast Artillery Field Manual. (C. A. F. M.)

Vol. I. Harbor Defense, Railway and Tractor-drawn Units.II. Antiaircraft Arttllcry Units.

)

(A. C. F. M.)

(E . F . M.)

Air Corpl Field Manual.

Engineer Field Manual.

Vol. I. Enginef'r T,'oops.

II. Military Engineering.

Signal Corps Field Manual. (S. C. F. M.)

Vol. I. Signal Corps Troops.II. E}ivna~ Corps Operation',



FOREWORD'

BUF;ic l~~lel(l l\Ianual, Volume III, Basic 'Y{'upons, will be

VUolll';hl'tl in six parts, as follows:

l'AR'l' ONE. Hlile company. (Each chapter of Part One will be pub.

11Mhl'dUti a llCIlarate pamphlet.)('hupter 1. Rifle marksmanship.

2. Automatic rifle marksmanship.

3. Automatic pistol markflmanshlp.

4. Instruction with the buyonet.

5. InHtruction with huntI antI rltle grenades.

G. Musketry. .

PAIIT Two. I.'ire-control Instruments.

Chllr1tpr 1. Machine-gun InstrUJDlmts.

2. 31-mm. gun antI 3-lnch trench mortar instruments.3. Care, rppalr, antI adjustment of instruments.

PAll'r THlnac. Machine-gun company.

Chupt('r 1. Mechanical training with the machine gun.

2. Machine-gun marksmanship ..

3. 'J'echnllJue of machine-gun tire, direct laying.

4. Technique of machine-gun fire, Indirect laying.

5. Barrages anll concentrations.I'AIt'!' I"OUR. JIowltz"r compnny.

Chapter 1. Mechanical training with the 31-mm. gun anll the3-lnch trench mortar.

2. B1-mm. gun antI the 3-lnch trench mortar mnrks.

manshlp.

3. Technique of the B1-mm. gun and the 3-lnch trl'nch

mortar fire.I'AItT l"Ivm. Combat practice firing.

Chaptpr 1. General.

2. IWJe company.

3. Mllchin,,-gnn company.4. Howitzer comllany.

I'ART 81x. AnUllh'craft marksmanship-Infantry wenpons.

ChuPh>r 1. Gl'n(~ral.

2. U1t1eand automatic rltle.

3. Machine ~un, call1H'r .30.

v



1~

7-22

23-27

28-36

37-48

49-52

53-54

5.H8

TABLE OF CONTENTS

Para-CI graphs. HINer 1. 1\J echllnlclIl trlllning with the machine gun, callber .30,

M11l17.

Seetion I. Description of machine gun_._ ••• _._._._._._._._.

II. Disassembling, assembling, head-spaoe adjustment,and chunging purts. •• • ••

III. Care and cleaning of gun, barrel, and tripod. •IV. Immediate action_. •• ••• •

V. M eehanlcal functioning_. ._. • ••

VI. StOjlpUges • ._. •• •• _._._._._ ••• •••••••VII. Tripod mountings • •••

CI VIII. Spare parts and accessories • • • •

Ilillter 2. Machine-gun murksmanshlp.

Section I. GeneraL • • • • ._. •• • 5H2II. l'reparatory exerclses_ •• ._________________________ 63-74

Ill. Course to be flred •• ._. • ._. •••• 75-76

IV. Conduct of range practlce • ._. • ._____ 77-99

V. Rule.~ governing record practltoe • ._. 100-115

VI. Construction of targets, ranges, and equlpment._. 11~119CI VII. Advice to Instructors. • ._ 120-126

IIlNer 3. Technique of machine-gun tire, direct laying.Section I. GeneraL • • • • • • ._ 127-131

II. Cone of fire and beaten zone • 132-133III. RllDge detennlnntion and windage • 134-140IV. Classes of flre • • • ._ 141-144

V. Target designation • • • 145-147

VI. Fire dlstrlbution • •• • •• • ••• ... 14S-155

'In. Overhead flre • • ._. • ._._ 1~165

VIII. F'loal protective lines and sectors of fire •• ._._. 16&-171IX. Runge cards. •• • • •• • 172-173

X. F'lre controL • • 174-176

XI. F'lre orders • • • ._. 177-179XII. Direct laying prohlems_ • • • 180-182

Xln. Direct la)'lng on landscape turgets at 1,000 inches .•• 183-192ell XIV. Tests of training in direct layio:l • • ._ •• 193-200

IIllter 4. Technique of machine-guD fire, indirect la)'lng.,.' Section I. GeneraL • ._. ._. • 201-296

II. Theory of indirect luying ._. • • 207-208

Ill. Obtaining map data for a single gUD •• ~210

IV. Obtaining map data for guns grouped In battery • 211-218

VI l

Pages

1-2

3- 14

15-17

1&-21

n-27

27-30

31-32

33-37

3fHl

41-55

57-.58

58-69

00-73

73-75

7~79

80-82

82

84-86

87- 89

90

91-98

9lH03

104-106

1~109

11()"111

112-113

116

121-123

123-124

125-126

127-132

132-133

140-148

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__ __ _ _ _ __ __

__ __ __

__ __ __

__ __

__ __ __

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VIII TABLE Ol' CONTENTS

1'1 ra-Chapter 4. Technique of machine-gun flre-Continued. j.;mphs 1'#

Section V. Obtainingdatawithoutamapforasinglegun 210 ....223

VI. Obtaining data without a map for guns groulled inbattery 224-225 l!ii~l~

VII. Laying and maintaining laying 226-228VIII. Searching reverse slopes 229--2:~2

IX. Defilade.l flring positions 233-234 If

X. Training on landscllpe targets at I,OOO-iIwh I\nd atunknown short ranges 235--2:16 H;g.-I,;

XI. Tests of tmining in ill(lirect laying 237-244 li3~1

Chapter 5. Barraa.:es and COllcentrations 245--258 17.r

I

14!1-

J!j/yll1Ii3~

1



U" A N I ',' 1 _11.~ •• ~.H. (f1./V I "y \0 WAn. I>EP.UfDI EXT,...0, 1 [ ,,- J]> , AS"I~GTON, (l1/1U/!"!1 2. !!).Jli,

j, .a~le 1~'j('Jll :Hllllual, VOIUllH' III, Part T11n'(', J une 10,W::::.

, IS <'llll)lgpll llS fono\\'~:

BASIC FIELD l\lANUAL

VOLUME III, BASIC WEAPONS

PART THREE

MACHINE-GUN COMPANY

I I (The matter contained herein supersedes TR 150-35, July 20, 1926 (in-

Udlng C I, January 2, 1929), 240-10, December 19, 1923 (including C 1,

l11.nuary 2, 1926), ll.nd 240-15, Febn'ary 16, 1925 (including C 1, February

5, 1926: C 2, January 3, 1928: and C 3, January 2, 1929).)

CIIAl'TER 1

,~mCIIANICAL TRAINING WITH TIII~ l\[ACIIIXI'~ GUX,

CALIImU .30, 1\11917Paragraphs

!o;.:('TIO~ r. Dpscrlpt Ion of lIlachiJH' l:'11II_______________________ 1-6

II. nIHllM~.lIlhling, IlRM('m1.>l!ng,wud-MI)llce adjustm4'l1t. unuchuJ lgIJ lg \lurtM 7-22

III. Cure ur.J cipnlling of ~UI1, harrt'!, Ilnd trl\lod :;!:~21IV. IllllllPdiate uetlon 2S-~()

V. Me'chunlenl fllllctioJ ling--------------------------- 37-48VI. SloppagNI 4!}-52

VII. l'l'!!J()U J IIountiJ ll,"s 53-54

VII I. Spnl'e \lurts uJ ld uc('psMorl«'s .':/;;-51'1

SlOCTIO:-; I

]>J<]:-;CHn'TIOX OF l\IAClIIXI'~ GUX

1. Type.-'l'he H)'owning lllllehine gun, ('nliher .30, :\11917, Is

I'l'('oll OPl't'lltell, hdt fl'd, und wuter coole(], The fone of recoil,

I'hnlJlIr to Uw "kkk" in the 8houhler rifle, is utilized to perform

th(~Vllrl()n~ lIlel'llllnlcal opel'Ht!ons of withdrawing the cllrtrillges

f)'OIIl the hcIt, ]llulling tllPm into the chumher, cocking and firing

the /;\111, unll wiUH]rllwing IIlHl ('jpetlng the ('mpty ca:-:~.

2. COoling system.-The burrel is. surrounded by a water

jllckpt which llO](]s nbout s<,vell pints of water. The water

lll.:-;Ol'hslhe IlPut genel'utell In llrlng the gun find thus pren>nts

;1Ie 1lurl'el from hecoming oVl'dwuted. 1.'he steam escape tuhe is

Ol'utel] III the top of the water jacket and consists of two

1

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~

-



I

I

I

2 "ASIC FlEW MANUAL 1

tubes-the inner and the outer. The inner tuhe hU8 a hole Ilcor

each end which allows the steam to escape. 'I'he outer

which is the shorter of the two, slides freely on the i1l1lPl' tuM I

and in the elevation or dellression of the gun the forte ofgravitJ' causes this tube to mask the lower hole, tIlU~ preventlug

the escape of water from the jacket. 'I'he upper hole, whit'h

uncovered by this movement, allows the steam generated:

throu~h firing to escUile through the inner tuhe to the condpn8

ing d~vice, which is immer8ed in the water box.

3. Feed belt.-The feed belt Is made of woven fubric wltb

loops and has no metal parts except 11 brass strip at each (.utlto facilitate loading. t4. Mounting.-The Browning machine gun is USllllI11

mounted on the :\11917 tripod. '1'his tripod is describecl

Section VII..

5. General data.-General data of the Browning mllchine J.,'l1J1

are as follows:

Weight of gun, without water (poulld8) 30.00

""eight of gun, with water (p011lHI8) ---__________ 3li. 76 i

Weight of belt, empty (ounces)__________________ 7.5 I

Weight of belt, filled, 2;:10rounds, l\l1!lOli (pouwls) 1:1.~;:;

Length of barrel (inches) --------_______________ 2.t, 00

Sight graduated to (yards) 2, GOO,

Hate of fire, l\11006 (shots per minute) 400-;:;25 I

Muzzle velocity (theoretical) (feet per sl'('onc1)___ 2,700

Muzzle veloeity (tlworeUcnl), l\I-I (feet per

se('ond) .:. -:_______________ 2, (WO I

Weight of tripod, MUH7 (vouncl~)__ 48

"~eight of tripolI, 1\11918 (plmncls) 4:1

6. Front and rear sights.-a. The front 8i~ht i~ mnde up otthe front-sight blade and the front-si~ht bU8e. The hladl~ 18

dovetailed into the base in such a way us to. allow H

adjustment and is held in place by the front-sight screw. 'j']le I

base screws fasten the base to the end ('ap. They are screwetl

in place and then fi\f'd flush with the base.

b. The rear sight (fig. 1) is adjustahh~ for windage, and drift

Is offset automatically by the construction of the rear-sight

leaf.1

c. TIle leaf-anll-slide assembly Is mount('ll on the

base, which in turn Is pivoted on the fIxed base, the latter b(.lng

tube,'

l Is'

'

11

I,

I

1

_

-

!-------------

--------------

latPI.11

movlIIJ

I



BASIC FIELD :MANUAL 3

MOVABl.E 45ASl:

ADJU.1TINO PLATe

F'l)( ED .l1A.3f.:

U.VATINf1 ~CR!W HJ!AD

:~eted to the cover. The windage-screw assembly is seated

i the fixed base, and by turning this screw the movable base

th its assembled parts revolves about its pivot. This pro-

Vdes n mechanical means for making allowances for the force

lot the Wind. It also provides a means for measuring andllyid ng, off Sma11angles •. 'Ihe rear-sight leaf is graduated in ~'af(ls. The wind-

gauge arc is graduated in mils.

W1NDA(JE JCQlW lfNOB........

....}<""IGVRE t.-Rear sight

SEICUON II

.. nISASS~~l\InLING, ASSEMBLING, IIEAD-SPACl<J AD.JUST-

MENT, AND CHANGING PAnTS

t "T. General rules for disassembling.-a. To prevent. damage

t~ the rear sight, whenever the cover of the gun is to be raised... le rear-sight leaf must first be raised Exception to this ruleMU b .tl .e Ilermitted ollly in companies in which all guns have

tt~COVerso construeted that the reaN;ight lellf can not strike

1 lieWater jaeket when cover is rllised with the rear-sight leaf

n tl down.

~



BASIC FIELD MANUAL

:Ill'RAMJ!

Ml!fXIf lOCH

LJARREL ZXTtN.:J/ONJlREl..

FIGURE 2.-Mechanhml In lJaekward position

con:J7"lA/t( 1lIb! (OUT£R)

"'7"l:AM 1f!U (/mm~)

4

b. The cover will be rah.e<1 by gripping the rear-sight base.

and not the sight leat, windage-screw knob, or rear-sight thumb j,

nut.

c. A <artrl<!ge ts the onty tool reqntred for disos"emhtlng thegun.

8. Removal of groups from the gun.-a. Backplate.-(1)

Pull back on the latch and raise the cover. 'Vith the left ban0

4ull back the bolt handle an<1bold it in the rearmost position.

(2) Insert the rim of a cartridge in the slit in the end of the

<1rlving-spl'ing 1'0<1. With the slit hori7-ontal, push in the driv-

ing-spring 1'0<1as far as it" will go and turn it clockwise on'~-

quarter turn until the slit is vertical, so that the lugs on it willengage in the undel'eut recesses in the bolt.

(3) rush the bolt houdle forward ohout 8U iuch to free the,

rear end of the driving-spring rod from the backplate. j

(4) I'ush the latch forwar<1 and lift out the backplate.

b. Bolt halldlc.-PuU the bolt aU the way back and remove"the 1,.,lt houd1e. oj

c. Rolt ..:-.puU the bolt out of the rear end of the receiver.d. Lock fra Inc.-Push in on the trigger pin through the hole.

on the right side of the receiver with the point of a bullet. Pull

lock framE', barrel extE.'nslon, an<1barrel out until the lower rear

lug~ on the harr~'l extE.'nsloudrop down behind the b(}ttom plate.

lIold the lock frame firmly an<1push forward on the accelerator.

This fo;('pIlratesthe lock frame and the barrel extension.

c. Barrel c.rten8i~m and barrcl.-(l) Pull the barrel extensionand the barrel out to the rear.

(2) Un~('rew barrel extension and. the barrel.

,. Latd'.-l'u ll the latch to the rear until it separates fromtho top plate j

.

.

" '~

"

"



BAi'IC }'IEJ~D l\IAXUAL 5

U. Latch 8pl'ing.-Lift the latch spring from its pin in the

1l1tch.

h. Cover.-(i) Turn cover-pin spring up and draw the assem-

Ilbl pin out to the right.

(2) Hemove the cover.(3) Lower rear-sight leaf.

9. Sequence in assembling.-In general, the groups are re-

NUcpd in the gun in the reverse order to that in which they

are remoyed. There are certain necessary precautions in con-

ll(\ction with assembling which must be observed in order that

the parts may be placed in the gun, and in order that they may

fUllction properly after the gun is assembled. If the gun wiiI~o together at all, failure to observe these points will result

in failm:e of the recoiling parts to go fully forward when the

driVing spring is released.

10. Replacing groups in the gun.-a. Replace coyer. Insert

cover pin and lock it by turning cover-pin spring forward into

!'Pcessin the trunnion block.

'b. Insert rounded end of latch spring in cut in rear of insideof latch and place hole in spring over pin, bent side of spring

aWay from the latch. Holding spring in place with the fingers,

llush the latch on to the top plate from the rear, free end of

Nl1ringto the front. Push up on latch spring to start the free

('llu of the SIJring oyer top plate, then force latch home. If~m'infl is a,(lo1C'Cdto slip fl"0111- Us seatin[/ the la,ten uill not

1l1rl-Ot;onand the 81Whl[/ will ja,m the latch. so that it can notbe removed 1rithout IJrcaking.

11. Head-space adjustment.-a. Oene1'01.-(1) If the gun is

tll function correctly, the head-space adjustmf'nt must he malIc

lIroperly. By head-space adjustment is meant the adjustment

or the ~pace between the rear 'end of the barrel and the front('lid of the bolt so that the bolt will press firmly against the

11118e of the cartridge when the gun is loaded to fire. This

lilljustment is made by screwing the barrel into the barrel

('xtension. If the head-spnce adjustnwnt is not tight enough,

tile explosion of the cartridge will CflUse the rear part of the

hrnss Ilowder case to blow backward anll pull the case in two,

II'flving the front part in the chamber and preventing the en-

1rance of the next cartridge. If the adjustment is made too

tl~ht, the recoiling parts either will not go home so that the

~Ull can he fired or the gun will fire sluggishly. Usually the

trIgger cnn not be pull(\ll. Great Cll rc must be taken in mnking

"



6BASIC FIELD MANUAL

the adjustment, as prescribed in (2) below, and in testing

the adjustment after the gun is assembled, as prescribed in bbelow.

(2) Start the barrel threads into the barrel emtension ana stop

at the beginning of the clicking sound of the barrel-locking

spring. Remove or raise the emtractor, place the bolt into the

guides in the. barrel emtension and shove it all the way home.

Lock the bolt to the barrel emtenslon by pUllhing breech lock up

into its Beat. flola it firmly i,n that position. Screw in the

lJarrd until a rcwiJltance other than tlla,t causeeXby the barre~

locking 8pring i-8 felt. Be sure that the breech lock is stin heldfirmly up in its scat in the bottmn of the bolt. Release the

breech lock, remove the bolt, aneXscrew up the barrel one or one

and a fraction notcMs, depending upon whether the tooth of the

barrel-locking spring i-8 in a notch or between two notc;~es.

(3) The head-space adjustment having been made, place

barrel and barrel extension in gun together until the lower rear

lugs of the barrel extension are against the bottom plate.

(4) Take the lock frame in both hands with the index fingers

under the accelerator. Place the claws of the accelerator in

front of and against the T lug. Insert the front projections of

the lock frame into the slots of the barrel extension and push

forward until the accelerator turns backward and locks the lock

frame to the barrel extension. PUsh down the tips of the ac-('elerator to insure positive locking.

(5) Raise parts and push them into the gun, forcing the

trigger pin inward' to clear it from right-side plate and push

fonvard until a click Is heard as the trigger pin springs out intothe hole in the right-side plate •.

(6) Push Cocking lever forward and insert bolt, pushing down

on rear end of trigger to pre~nt ejector from tripping theaccelerator.

(7) Insert the bolt handle through the large opening at the

rear of the slot and push it forward' about 1 inch, being sure

that the collar on the handle Is inside the right-side plate.

(8) Push forward on latch and replace the backplate.

(9) Hold the bolt handle fully back with the left hand.

l>lace the rim of a cartridge in the slit in the end of the driving-

f'pring rod, and turn the rod one-quarter turn to the left (coun-

terclockwise) until the slit is horizontal. This releases the

driving spring. Allow the bolt to go forward Pull the trigger.



BASIC }'IELl> l\IAXUAL 7

bJ Tests for correct a,djludmcnt.-A positive rule for head-

Rpace adjustment that will fit all cases can not be given, and

the following tests must always be ap11liedprior to firing the

gun:

(1) Work the bolt by hand two or three times, and in casethe breech does not lock smoothly, or the holt handle does not

go all the way forward, unscrew the barrel one notch.

(2) Raise the cover and the extractor. :\loYe the bolt

Slightly to the rear by means of the bolt handle. There must

be no rearward mOVCll1wntof the boltinde])(mdent of the barrel

Prior to 1ln.lockillg of the breech. If the bolt moves rearward

Independently of the barrel the adjustment needs tightening.C. Quick adjustment.-After the correctness of head-space

nUjustment for a particular gun and barrel has been established

by aetual firing, the proper notch for head-space adjustment

khould be marked und the munber of clicks required to screw

the barrel up tight in the barrel extension from this point with

the bolt removed should be counted. Then to adjust head space

qUickly, screw the barrel in until the proper number of fullturns has been made and stop with the barrel-loeking spring

In the marked notch, or screw the barrel tight into the barrel

extension. and then unscrew the required number of clicks.

12. Detailed disassembling of bolt (fig. 3).-a. Extractor.-

Turn extractor up and remove it to the left.

b. Driving-spring 'rod (fig. 4).-(1) Grcat care should be exer-

('ised in ,'cl11A(Yvinghe drivil1g-.'spring ,'od from the bolt as theforce of the driving spring '/,Chen'released can easily cause the

"od to slip away from the hand. If a person is strU('k lnJ the

"od very serious injury tnay result. To remove driving-spring

rod, place the protruding end of the rod on the table or a piece

(It wood. With the bolt firmly grasped by the right hand (palm

()f hand over the top of bolt), press down und at the same time

turn the bolt one-fourth turn to the left until the driving-spring

rod pin leaves its recess in the bolt. Slowly release pressure on

t he bolt, allowing it to l'ise under the action of the driving spring

Until about 3 inches of the rod protrudes. With the left hand

grasp the protruding portion of the rod and spring; raise the

holt from the table, at the same time keeping the rod and spring

In their same position relative to the holt. Separate the rod

/Iud spring from the bolt with a quick jerk. The quick, separat-

Ing jerk will not allow the spring to kink.



8BASIC }"n:LD MANUAL

(2) Separate the driving-spring rod and the driving spring.

c. Cockillg-lct'cr IJ;n.-Withdraw to the left of the bolt.

d. Cocking let'er.-Llft out cocking lever.

e. Sear.-Helease firing vin b~ pushing down on sear. Hold

holt in left llanu, front end toward body, top up .. With pointof bullet placed near end of sear sllring push downward and to

the rI~ht to seat It in cut in lxllt. This releases the sear, whichwill drop out at the bottom of the bolt.

,. Scar 8[Jring.-(1) Turn the sear l'llring back to the left toclear the cut.

..,..&l;;:;:::=::.:......jj

-:~;;--&-=--I'IR1:G PINMWwy"'''!!I/IIttWollIWo.l~ SEAR~RIV/N(J .'JPR1N(J

. ro;;; =~Sl'AR",PRINGPIND1lfY1NG $PRI!(O ROO- - -SEAR 3PRINIJ

COCKING --'oc[([;a LEV~R PIN

FWt:RE 3.-llolt gronp

(2) Push "ith nose of bullet in hole in bottom of bolt to startthe sear.spring pIn up. To complete the removing of the sear

spring, place the tOl)end of the c()('king lever under sear springnnd pr~' down against the edge of bolt.

g, Pir;IIg 11;n.-Tilt the rear el\(l of bolt down and the firingpin will fall out.

13. Assembling bolt.-a. Place firing pin in bolt, striker

downward llnd to the front, and llush forward until the striker

projects through the small hole in the frollt of the bolt.

b. Uepla('e scar spring, by forcing sear-spring pin downward.

lly pushing wIth cartridge on top of pin, avoiding pressure Oil

sprIng propt'r.

c. lIold holt in left hand, front end toward the body, top up.""ith point of bUllet placed near end of spar spring push down-

ward and to the right to seat it in the cut in the holt. .

d. Push sear upward from the bottom, notched projection tothe front, and bold with first finger of left hand while prpssing

t '

~ ~

~



BASIC FIELD l\1~~NUAL 9

downward and to the left on the sear spring with a bullet to

engage the end of the sear spring in the sear.

e. Heplace cocking lever, taking care that rounded nose onlower end is to the rear so that it ,vill properly engage rear of

l'ecess in firing pin.f. Insert cocking-lever pin from left side of bolt. Push upperenll of cocking lever to the rear before inserting pin, as the

holes are thus placed in alignment.g. Cock by pressing forward on cocking lever. Hold cocking

lever to rear and press down sear with bullet to release firingJlin and test correctness of assembly.

h. The same care should, be exercised in assembling thAJ driv-

ing-spring rod to the bolt as is exercise(l in 1'cmo'L'ing it . Place

driving spring on driving-spring rod. With the back end of the

rod resting on a table or a piece of wood, gather as much of the

spring on the rod as can be held compressed by the thumb and

fingers of the left hand. With the bolt securely held in theright hand, front end of bolt in palm of hand (fig. 4), slip the

holt over the end of the spring. Push downward to compress

Spring and allow driving-spring rod. pin to enter the slot in the

holt. Turn bolt slowly 90° clockwise until the slot in the rod

is crosswise to the slot in the bolt.-£. Insert the pin on the extractor in the rear of the two large

holes in the left side of the bolt, extractor pointing up. Turnextractor downward toward the front to engage the collar on

the extractor under the collar cut in the bolt.

14. Detailed disassembling of lock frame (fig. 5).-a. rush

out trigger pin from the left side of lock frame. Remove trigger

and trigger-pin spring.b. Push out the accelerator pin and remove the accelerator.

c. Hold lock ..frame with left hand, projections pointing up-ward, slot to the left, separator between second and third

fingers, first and second fingers gripping barrel-plunger spring.

With the thumb of the right band, press down and out on barrel

plunger to disengage plunger-guide pin from slot. Allow spring,

carrying plunger, to rise slowly. Lift out spring and remove

spring from barrel plunger.15. Assembling lock frame.-a. Assemble barrel-plunger

sIn'lng to barrel plunger. Hold lock frame with left hand, pro-

jections pointing upward, slot to left, lock-frame separator be-

tween seeollli UlHl tbird fingers. Seat end of barrel-plunger

98!l53°-32--2



10B.\src FIELD MANUAL

FWl"RE 4.-:\lethod of all8l'llIbling and disassembling dl'lvIng sprIng,

dl.h'Iug-llprIllg rod, llnd bolt



BASIC FIELD MANUAL 11

Spring in recess in lock-frame separator, barrel-plunger guide

Pin facing slot in lock frame, left. Hold spring with first and

second fingers of left hand. 'Vith thumb of right hand press

down on end of barrel plunger until barrel-plunger guide pin

cnn be seated in slot. Care should be taken that plunger under

action of spring does not slip out of hand.

0. Replace accelerator, tiPS up, rounded surface to the front.

InRert accelerator pin, taking care that both ends of pin are

fluf.lhwith the sides of the lock frame.

I

]

e:::=-- ~l ~-TRIGG£R

TIP"' it.:. (l e . O-lWIULPUlNtl<R

f}) . ~-ACClLERATOR PIN

. ACX1!.c.ERATOR ~_nARRI:r.PWN(j£R.3PRlN6

TRIGGER PIN

!/j-TRIGGER PIN .sPRING

FIGURE 5.-Lo(~k-frallle group

c. Pm5h front end of trigger up between separator and

SPllcer, placing the center in its square seating. Place spring

on trigger pin, small end of spring toward head of pin, and

1nfolertpin from the right so that spring is seated in the recess

provhled.16. Detailed disassembling of barrel extension (fig. 6).-a.

Pry Imlle't under front edge of the barrel-locking spring and

pun it out forward.b. Push out breech-lock pin and remove breech lock.

17. Assembling barrel extension.-a. Place breech lock in

Its slot, taking care that the double beveled surface is llP and

to the front. Insert breech-lock pin and insure that both endsof pin are flnsh with sides of barrel extension.

b. Insert barrel-locking spring in seating in left side of barrel

exten!'iion,hook inward, and force home as far as it will go.

~

~



MeeCH l.OCK PIN

/=

R\SIC FIELD l\-IANUAL

I"IGl"RE 7.-Cover group

M;l:~r"u~rc;;:. Q

/JAR/II!l. l.hcXINO SPRINrJ

12

18. Detailed disassembling of cover.--a. Turn belt-feel

lever-pivot Spring outward and remove belt-feed lever pivot.

b. Draw belt-feed lever from belt-feed slide and remove slide

c. Insert nose of bUllet between cover-extractor spring nnnotch in cover-extrnctor cam. Pry out on spring to disengag(from cut.

19. Assembling cover.-a. Pluee forke(l end of cover-extrac-

tor spring under stud on Cover. Press downward with thumbon other end of spring, a t the same time PUshing toward stud,

and sea t projection of spring in notch of cover-extractor earn.

b. RPplace belt-feed slide in its grooves in cover,' taking care

that the Pllwl is pointing to the right as Cover goes on the gun.

c. Place front end of belt-feed lever in cut, stud on lever awayfrom COverand to the rear. Insert belt-feed lever-pivot spring

at rIght angles to cover so that lugs on pivot will pass through

cuts in cover. Turn spring inward toward base of rear sight

~



BASIC FIELD l\IANUAL 13

Until lugs engage on underside of cover and spring locks in

place.

20. Disassembling of, parts dismounted only for repair.-a. Shock-absorbing group.-Unscrew adjusting screw and re-

Illove adjusting-screw plunger and spring. Remove buffer disks,

bUffer plug, buffer ring, and buffer plate through the rear end

of the grip. Replace in the reverse order.

b. Belt-holding pa.wl.-{1) Hold <lown the belt-holding pawl

and withdraw the belt-holding pawl split pin to the rear.

(2) Lift off the belt-holding pawl.

(3) Lift the belt-holding pawl Sl)ring from its seating.

(4) Replace in the reverse order.

c. Steam tube.- (1) Tbe steam tube need never be removed

Unless it becomes so clogged from the use of dirty water that

8tenm will not pass off, or the outer tube becomes stuck so it

Will not slide back and forth on the inner tube when the gun

lij held in the hands and tipped forward and backward. Great

care nlust be used to prevent danlage to the threads of the

81eam-tube front plug, and it should never be removed except

Under the supervision of an officer or by an experienced

Inechanic.

(2) Stand the gun with the muzzle up and water jacket

vertical. Remove the steam-tube front-plug screw. Place the

large screw-driver blade of the combination tool in the slit and

Unscrew the steam-tube front plug until the threads are dis.

E>ngagedand tbe steam tube can be lifted out.

(3) To replace, stand the gun exactly vertical, as prescribed

ill (2) above, and insert the steam tube. Gently screw in the

threads, stopping at once if there is any undue resistance. The

gUn flIld tube must be exactly vertical to insure that the conical

('lid of the tube enters its seating in the trunnion block. Forc-

ing the screw against resistance will damage the threads. If

It does not screw in easily, unscrew short distance, be sure

the water jacket is vertical, and try again until threads screw

In smoothly. Screw in tight without excessive force, and then

Position the notch in the rim of the plug exactly on the round

COuntersunk recess for the front-plug screw, unscrewing part

ot n turn if necessary. Replace the screw and screw it firmly

down into its countersunk sf'ating. If the notch in the rim isnot engaged by the screw head, the steam tube will not be aligned

in the front-end cap to permit lhe escape of steam and the

Wllter jacket will hurst from the steam generated in firing.

~



14'BASIC FIELD MANUAL

21. Packing the barrel.-Asbestos packing is applied at the

muzzle and breech ends of the barrel to prevent leakage froIH

the water jacket. The amount of packing must not be excessive,

since the friction caused thereby will interfere with the actionof the mechanism. The proper amount can only be determined

by experience and trial. Usually a piece of packing about an

inch longer than the circumference of the water jacket is cor.

reet. It8hould be Well saturated with oil before being applied.

a. Pocking the breech. end.-Place packing in cannelure and

press home with screw driver and thumb. Wind it around,

pressing up against the wall of the cannelure. As the eml i~

crossed on the first turn, see that it is bound down flat. On

the last turn force the end under and see that it is bound down

fiat and worked well in. Insert breech enll of barrel into the

hole in the trunnion block and push forward gently, twistingbarrd until pa{'king is worked down to fit. .

b. Pack£nfl the. muzzle end.-Wlth the gun assembled, alloW'

the bolt to go forward or trip the accelerator so that the barrel

is fUlly forward. Remove the muzzle gland. Wind the pack-ing in even layers about the barrel with the first coil as close

as possible to the end cap. Push back the mUZzle or draw back

and hold the bolt, at the same time guiding the packing into its

seating. Screw in the muzzle gland and test friction of the

mechanism by pulling and releasing the bolt handle several

times. It there appears to be too much friction, remove one or

two coils of packing. The muzzle gland must be screwed upso that its shouhler is against the metal of the end cap and isJ:ot stoPpt'd by jamming against the packing.

22. Methods of changing parts.-a. Worn or bulged bar-

reIB.-The necessity of saving water In the water jacket dppends

('nUrely upon prevrliling conditions. In heat of battle, water

may not be obtained readily, Time also may be of the utmost

import:lnce. It it Is necessary to save the water in the water

ja('ket When chnn;,,"ing barrels, one of the following methodsshould be employed:

(lL First methfJd.-(a) Remove the bolt from the gUll.

(b) l'u!"h in on the trigger pin and pUll the lock frame to therear from one-fourth to one-half iu{'h,

(c) Remove the elevating pin and depress the muzzle ofthe gun. .

(d) Hold a plug at the mu.zzle of the barrel. (The steam.lllug cork wrapped in cleaning pat<'hes is suitable.)



I


(e) 'Vithdraw the lock frame, barrel extension, and barrel

to the rear. As the barrel is withdrawn, follow it with the

}llu~or steam-plug cork and insert it in the hole in the end cap

Ill' Inuzzle gland through which barrel has been withdrawn.

(1) Place a plug or twisted patch in the muzzle of the new

barrel.(0) Connect the barrel with the barrel extension, being care-

fUl to secure the proper head-space adjustment.

(h) Replace the groups in the gun. When the muzzle of the

1l1'W barrel passes through the hole in the end cap, remoye both

th(~plug and steam-plug cork. Hun a patch through the barrel.

(i) Care must be exercised in removing and assembling the

1181'1'eln order not to disarrange the packing. Very frequently

III assembling the new barrel the front packing is carried (Jut

hy the lfluzzle.(2) SCC01Hl method.-Drain the water from the water jacket

Into the water box. As the water jacket has to be refilled after

the new barrel is seated, this method will require more time, than the method described above.

b. Changingparts.-If it is imperative that fire be maintained

. (Ir Immf'diately resumpd, a broken minor part should be re-

I'lnepclby substituting the complete spare part which contains

it. Thus a broken firing pin woul(l be remedied by changing

holts; a brokpn ejector by changing extractors. Later, as oppor-

tunity permits, the small parts will be repaired or replaced inol'(ler to make the larger part again available for use. In case

tIl(~('omplete bolt has beeR.changed, a check should be made of

the head-space adjustment.

SJ<:,CTIO:-' III

CARE AND CLEANING OF GUN, BARREL, AND TRIPOD

23. General care.-It is essential that the gun be maintainedIII the best mechanic-a1 condition at all times. It must always

lie kept clean and covered with a light coating of oil. particular

Ilttentlon must be paid to the bore. Care and cleaning will not

ll(~confined to the gun alone but will include the tripod and all

IH'ecs8oricS. Belts and ammunition must be kept clean and dry.

24. Points to be observed before, during, and after firing.-

'rhe following table of points to he observed before, during, andUfter firing will be found convenient as a guide for the properI .Or. of the gun. ItwlJ l also serve as a gniJe for in"" ••Uon.

~



16BASIC FIELD MANUAL

!

,I

,I

I

I

I

I...2S<IIt::

I

I

I

I

!t:

I

I

I

i

I

I I I

I •

I -o:i !i

: ~ !.I

E ] .~~ ~

~ ~ ~ ~



!

f

BASIC FIELD l\IAXUAL 17

25. Care in cold weather.-a. Thin the lubricant on the work-

in~ parts with kerosene or gasonne until gun is warmed by

tiring.b. See that water at the gun does not freezt~.

o. Test the gun fn~quently to S('e that it functions properly.

26. Care during a gas attack.-a. Close lids of ammunition

hO)(Nl. .

11. Guns should be eIpaned as soon as possible after a gas

attack.

c. Oiling will prevent corrosion for about 12 hours.(1. Clean all parts in boiling watpr containing a little soda,

if available.

c. All traces of gas must be removed from ammunition with

11. ""lightly oiled rag; then thoroughly dry the ammunition.

f. Cosmoline resists gas corrosion more than lighter oil. ILl

lllally ('Xllo:-;urps,esppcially of long duration, ammunition treat-

(\11with sperm-oil evidences more severe corrosion than un-

r1ro/('cted cartrillges.

27. Care and cleaning of gun and tripod.-(A more de-

taiIe<l discussion of this subjed ('an be found in TR 1395-A.)

a. 7'he b01'c.-DisasHemble tlw groups from the gun. The barrel

"'ilh the barrel extension attaehpd is placell, muzzle down, in

;a V'NIHel containing hot water and issue soap, a sal soda solution,

or, laeking' theHe, hot watl.'r alone. (It is mo~t ('onn'nient to

('!I'Un the bore immediately after firing, as hot water is avail-

llbl{~n the water jaeket.) Use the cleaning rod with flannel

rllllf('h to pump water baek and forth through the bore for about

I()nl~minute. 'l'horonghly dry and clean the bore before applying

lit (:outing of lubrieating oil.

. 11• Afoviufl 1/ort8.-'1'he moving parts should be kc>ptclean and

}IIIJrleatPllhef()I'{~,during,. al1l1 after firing'. Avoid pulling a

I Jilt/'tlyempty helt throu~h the feell olwlling, as the lint and dirtI thllM ('ollpefell intprfc>re with the fundioning of the feed

1111'I'lr:llliHnl.

0. 71he tripod.-Keep nil threads lightly oiled. Avoid exces-

f\lv(~ oil from g'ptting into the spI'l'ations, ns dirt and ~llnd will

~;:JII(>ctherpln aIld int('rf('l'e with ]JoHitive hleking of the lpgs.

IhI' }Iintle should he 1'('mon'll oecllsiollally, deanI'll, nd lightly

°il",l \\'}\('re tlwl'e is frktion with the sll<'kpt. Oil should not be

i 111111'('11n the :-;I'atingof till' traversing llial, as it will cause dirt

to ('ollect awl interfere with easy dial ndjustment.

~

8.



18 BASIC FU:LD MANUAL

SECTION IV

IMMEDIATE ACTION

~8. General.-a. Dc(inition.-Immediate action is the

ate amI automatic aplllication of a llrohuhle remedy for )

machine-gun stoppage. Immediate action deals with the llIetllO

of redUcing stoppages and not the cause. Causes ofwill be discussed ill Hection VI. .

b. Scope of insfruction,-Instmction in immediate actloJ

shoUld pre('ede instruction in stoppages. No discussion as t

causes of stoPl)ages shoUld be permitted dming irnmediat:

action training. Instruction in the subject of stoppages Will,

include the allI)lication of the prescrihed fOl'm of

action to each t)"pe of temvorary stoppage stndied. ,

29. Duties.-Xo. 1 performs the imnwdiate action. No.2 i

the assistant to No. 1 and is expected to help him .in ever

wa)" possible to get the gun in firing cowlition when a stoppage

(lccurs. lIe will be al(\rt to earry out instructions which ,lIla5;

be given him by No. 1. No.2 is reslwnsible that the belt IS,into the feeclwa'~"properly and that the weight of the loa de

belt is not carried hy the feed mechanism, In addition, No.

will he responsihle that the ('over is latched and t.hat it

maius latched throughout the firing. No.1 may call for ru~

tured cartridge extractors, .. combination tOOl," or "cleaniOrj

rod." The rapIdity with which the immediate action is

plete<1(]('II('ntlsill a large degl'ee on the promptness withNo.2 supplies the required tool to NO.1 and his speed in

tormiIlg bis duties in reloading. The men are taught to

form immetliate action slowly and a(~curately at first. 'Vhen

suitable dt'~ree of proficiency has bt\en obtained, speed isLlnetl with accuracy. :

30. Relaying.-As the application of immediate action

likely to derange the laying of the gun, th(~ sight I';ettingthe laJing must always he cheeked before firing is resume

An aiming mark for each gun will be pointe(l out and

after eacb application of immediate action will be made aof the instruction. . ,

31. Firing with stoppages.-It Is desirable to conclude tIll"

training in imnll'diate action by following the theoretical il

struction and drill with actual firing of a belt containingIlUmber of prepared stoppages.

immed~

'

stoppage~

immediate]

fe

re

coJJ

WbiC pet'

pet

CO

aIl

relayiIl;

pal



r

i

I

I

BASIC FIELD l\IAXUAL , 19

32. Phases of immediate action.-'Vhen a stoppage occurs

ill firing, the gunner will be taught that the set of actions pre-

~erioed helow, or such part of them as is necessary to reduce

the stoppage, will be performed in the sequence, first phase,

8f'Condphase, third phase. He is trained to follow habitually

thl8 proce(Iure without any attempt to analyze the cause of thetl'OUble.

a. Pi"l!;t pllasc.-Gun -fails to fire.

(1) Pull holt handle to the rear and release it. (If bolt

handle fails to go forward, go to spcond llhase immediately,)

(2) Helay and fire.

b. Second Vha8c.-GUll still fails to fire.

(1) Uai:.;e the cover. (No, 2 removes the helt and the first

l'Ollndfrom the belt. No.2 holds this round until firing is re-

~Ulnedor until No.1 calls for it.) Place the left hand under

the receiver, pull bolt handle to the rear, raise the extractor,

IInd glance into the reeeiver.

(a) If a round remains in the chamlJer, call "Cleaning rod"to No.2, who removes the roun(I with the cleaning rod.

(1) If a round sticks in the T slot, call" Combination tool"

to No.2 and remove the roulHl with the combination tooL

(c) If a round is ('jected, examine it. If the round shows the

l'!ng mark of a sepnrat('d cnse, call .. Ruptured cartridge ex-

h'Qctor" to No.2, and remove the separated Cllse.

(d) If there is no rou11lIin the chamber or T slot, and none:Ii ejected, call "}~irst round" to No.2 and examine it. If it

Ii a short round and shows a nick Oll the rim, replace the belt-teed lever.

(2) Heload, reIny, and fire.

C. Third phase.-Gun still fails to fire.

(1) Place the left hand under the reeeiver, pull bolt handle

to the rear, and hold it.1 (a) If a cartridge is ejected, call" Bolt" to No.2 nnd change)(1]t8.

t (b) If there is no ejection, examine the fe<'IImechanism (ex-

I'actor, belt-holding pawl, and ('over), ancl replace defective

I

lllltt

(2) Reload, relay, and fire.

33. Usbg the ruptured cartridge extractor.--a. There aret\\'o forms of ruptun'fl ('urtridge extraetors. One is similar in

I f01'1I} to 11 cartridge. TI}(~M1\:.IV is of the same general form,

\"lth the addition of 11 lever handle.

I......

~



20 IUSIC nELD MANUAL .

b. To use the cartridge form, place it in the ffled way against

the cartriuge stops al1(l engage tl,le rim with the extractor OJl

the bolt. IIolu down the extractor with the fingers of the left

hand and draw the boIl to tlw renr. Allow the holt to go for'

waru slowly, guiding the ruptureu cartridge extractor downT slot to insure its entering the chamber smoothly. Allo,:

bolt to go fully forward, Wit,hdr:lW it slightly and let Itforward again. Strike forward on the holt handle with the

palm of the right hanu to insure seating of the ruptured car'

tridge extractor in the Sf'Illll'ated case. Place left hanu undet,

receiver anll pull the holt handle to the rear, catching the

ru[ltured cartridge extractor as it falls out. In usingruptured eartrhlge extractor, do not let the bolt handle fly for'

ward from the rear, as 11heshoulder on the ruvtured eartridg:,

extractor is likely to strike the edge of the chamber and make

hurl' on it, Which will prevent the full entry of a cartridge un J ,'

renll(>r the barr('l useless. '.

o. To use the l\Ik. IV, draw the bolt handle to the rear

"hang the bolt" by engaging the extractor-earn plungpr innotch in the rear of the extractor-feed earn. Insert the nose 0:the ruptured cartridge extractor in the chamber, handle

pU!o'hforwaru 11>l*'ut firmly in the separated case, and PUl~,Ib:l('kward on the handl<>.

d. Separated Cll!o'eS should be r('moved fWIll the rupture

cartrluge extractor so thll t it will again be rpady for use.

do this, the end of the rupturl'd eartridge extractor must bjunscrewl'd, the separated case taken off, Hnd the end screweon again.

34. Removing a round from the T slot.-a. IIolu back

holt and raise the extractor with the first finger of the rigb

hund. The round will usually fall out unless it has a thickor the T slot is defective.

b. If the round will not fall out When the extractor isUse the" combination tool." If the round is not below the

handle slot, insert the scre.w-drlver end of the combination toO,

through the slot under the rear end of the cartriuge and pr,

round up and out of the T slot, holding down the front end 01,

the cartridge with the finger.

o. If round is too far down the T slot for the insertion of tb]

combination tool, "knock it down." IIolu the holt handle tthe n'ar with the extractor raised. Place the screw-driver eI1

tilethe

g

the

un(

th

uP'

'1'0

tIl

riJ

r&ised b01t



f

I

I


through the top of the receiver into the top of the cannelure of

the cartridge and drive the round downward out of the T slot

hy striking the upper end of the combination tool with the palm

ot the hand.

35. Removing a case from the chamber.-If there is an

empty case with broken rim stuck in the chamber, call" cleaning

rC;d." Remove round from the T slot if there is one. Hold back

holt. Insert the deaning rocI from the muzzle and knock the

empty case from the chamber. Be sure the cflse does not stick

In the T slot. If several rounds stick in the chamber in close

SUccession,squirt sOllieoil on the ('hamber brush and thorougnlyElcruhthe chamber.

36. Test in immediate action.-a. Preparation.-The test

Iii prepart'd as follows: Four guns are set on a line with 3-pace

1IIter\'als. On each gun a different stoppage is prepared, the

reeei\'er covered with a cloth, ancI the firing pin released. At

l(!ast two of the guns will be prepared with stoppages which will

l'l'quire the execution of the second phase of immediate action.Identical targets are placed in front of each gun. The aiming

lllark for each gun is sueh that one uesignation applies to all

Of them; for example, "The aiming mark for each gun is to be

the black paster in the center of the target in front of each

RUn." After the stoppage has been prepared, the gunts so laid

that a slight manipulation of the traversing and elevating gears

Jlt llecessary in order to lay accurately on the aiming mark.'l'he sight setting on all the guns is the same. .

1). Procedure.-The man to be tested is called up and given

the aiming mark for each gun and the sight setting to be used.

lIe then takes the proper position at the gun. As the instructor

r('ll1oves the cloth from the receiver he announces "Gun fails

to fire," and the man undergoing the test immediately applies

the llecessary immediate _action. As soon as he has performedthe correct action at this gun, he presses the trigger, and then

the Instructor orders Next gun. The man moves as quickly

Us IlOssible to the gun next In order. Here he takes the correct

1l0lilitionwithout command and, as soon as the cloth is removed

(1'0111he receiver, applies the correct Immediate action. The

11l'ocedureat the remaining guns Is the same as at the second

gUll. As he presses the trigger of the last gun, the instructor

Iat the gun calls" Time," indicating that the man has completed

the test.

I ]2~~OO



BASIC FIELD :MANUAL22

c. Additional rules for test in immediate action.-(l)

guns are placed out of sIght and not in effective hearingtance of the men waiting to be tested.

(2) An offic-erOr noncommIssIoned officer is at each gun toconduct the test at that gun as well as to grade the man

(3) It, after apparently corr'ecting a stoppage and pressin(

the trigger, the instructor should say, "The gun still fails to

fire," the man taking the test then applies the next phase ofimmediate action.

(4) The officer ~r noncommissioned officer conducting the test

at <'Rchguo, or a mao detailed, performs the doUes of No.for the man undergoing the test.

d. Time allOlccd.-Two minutes. Time is taken from

instant when" G.un fails to fire" is called at the first gun untilthe instructor calls" Time" at the last gun.

c. Pcrformance._(1) The correct immediate action forstoIlpage is applied. .

(2) The gun is loaded.(3) The gun is laid.

(4) The trigger is pressed.

SF..cTION V

MECHANICAL FUNCTIONING

37. Trigger action: (fig. 8).-The trigger being pivoted, a pull

on the r('ar ('nd lowers the front end.. The trigger cams force

the sear down against the action of the sear spring. The searl

notch Is released from the shoulder of the firing pin. The firing'r

pin spring forces the firing pin forward to strike the primer. .

38. Backward movement of the recoiling parts (figs. 8

and 9) .-The explosion forces the recoiling parts (barrel, barrel

extension, and bolt) backward, locked together, about five-

('ighths Inch. During this movement the breech lock Is forced

down by the front projections of the iock frame acting on the

breeeh-Ioek pin. This unlocks the bolt from the barrel exten'

sion and permits the bolt to continue to the rear. As the barrel

l'xtension comes to the rear, the "barrel plunger spring is cow'

pre~s('<1and the rear end of the barrel extension strikes theaccelerator and turns It backward.

39. Backward action of the accelerator (fig. 8).-As the

accelerator turn~ baekward it strikes the bottom projections oIl

the lJOlt and accelerates Its movement to the rear. The clawS

~l

Tbe

diS

tested:

the

eacb



• BASIC FIELD l\IANUAL 23

Of the accelerator engage the shoulder of the T lug, locking the

harrel extension to the lock irame. . I

40. Backward movement of the bolt (figs. 8 and 13).-As

the bOltmoves backward the driving spring is compressed. The

bOlt brings with it a cartridge from the belt gripped by the

eJrtractor and an empty case from the chamber gripped in the

"r slot. 'l'!le extractor-cam plunger 'rides along the top of the

COCKINS LEvell,

JJACKPLATE.

~Ti .RCL EJlT£NJION

JjARR L EXTENSION

FIGURIIl9.-llnrrd, bolt, locJc frame. and barrel extension in

, firing position

'eJrtrnctor cam and extractor-feed cam until it is forced in by

the l,eveled pnrt of the extractor-feed cam. The extractor is

then forced down by the cover-ex'tractor cam and the plunger

~Dringsout behind the extractor-feed earn.

'41. First act of feeding (figs. 10, 14, and 15).-As the bolt

lilovefi!backward and the stud on the belt-feed lever moves to

:he right in the earn groove it forces the belt-feed slide to theeft. The belt-feed pawl engages on the left of the first car-

tridge, Which is held in position by the belt-holding pawl.

42. Cocking action (fig. 11) .-As the bolt moves backward,

~he uvver pnd of the cocking lever is forced forward, which



24 BASIC FU',LD :MANUAL •

brings the lower end to the renr. The lower end brings with it

the firing pin, thus compressing the firing-pin spring. The

shoulder of the firing pin engages the notch in the sear, which

is pulled upward by the ad ion of the sear spring, the triggel'cams now being disengaged from the sear.

43. Action of the driving spring (fig. 12).-:-When the rear

of the bolt strik<'S the buffer plate its remaining force is all-

sorbe(l in the fiher disks and in friction when the brass buffer

ring is forced over the buffer plug and expnnds ngainst the

inner wall of the grip. The driving spring then forces the bolt

forward.

IJZL1'

MLTHOlDINQ

MWL AND "'PRING

NLT '~I!D Ll!VI!R PIVOT/lND .3PR//'I6

FIGURE }O.-Helt feed mechanism

44. Forward movement of the bolt (fig. 13).-When the bolt

starts forward, the extra dol' is guided downward hy the actiOll

of the extrlldor-feed earn on the extractor-earn plunger. Thiil

causes the extractor to foree the cartrhlge down the T slot ill

line with the chamher. The ej(~ctor knocks the empty ease frolll

the T slot and holds the cartridge in line with the chamber.

The upper end of the c()('king lever is forced backward and the

lever end moves forwanl away from the rear of the firing pill.

45. Rele:lse of the recoiling parts (fig. 12) .-As the bolt

goes forward its bottom projections strike the accelerator and

turn it forwar<1. This ulllot'lUI the barrel extension from the

lock frame. When the accelerator has been tripped the barrel

extension and the barrel move forward, assisted by the barrel'[

plunger spring. Part of the forward force of the bolt aetil

through tho .,,'elorlltor to I'URhthe hlirrel ex'elislon forw.r~'



BASIC FIELD l\fANUAL 25

46. Loading and locking action (figs. 12 and 13).-As the

holt goes forward the extraetor rises as the plunger moves

fORWARD PO.5ITlON

BACfMARD POSITION

FIGUREn.-Firing mechanism

Illong the top of the extractor cam and the ejector moves out-

'vard, leaving the cartridge in the chamber gripped by the T

fllot. The extractor grips the first round in the belt and Is held

down firmly, ready to extract it, by the cover-extractor spring.

DRIYlNO 3MfN(J

ROD

TP/(}(JJ!R

FIGURE12.~R.e~ation of parts in backward position

~he hrpceh lock is forced upward by the breech-lock earn and

locks the breech just before the recoiling _parts reach the firing

1>osition. The breech lock engages in a recess cut in the bottom

of the bolt and thus locks it firmly to the barrel extension and

Ilgainst the rear end of the barrel.98953-32--3



'2GBASIC FIELD MANUAL

'OPER EXTRACTOR ~PRIN~

EXTRACTOR CA!1

FIGURE 13.-Extractlng nnll loadIng mechanism

&LT '~~,jLJDt!,

l'IGt:RE H.-Cover and shock-ubRorbinggroups

rXT1IACTOR CA!'I PUIN(JCA

FIGURE 15.-Barrel extensIon, bolt, ,and lock~frame group




47. Section action of feeding (fig. 10).-As the bolt goes

forWard the stud on the belt-feed lever moves to the left in the

caUl groove and forces the slide to the right. The belt-feed

IJuwlcarries tlJe first cartridge to the right against the cartridge

foltops,eady to be gripped by the extractor. The next cartridgei~ ('anied over the belt-holding pawl, which rises behind it and

holds it in position to ue engaged by the belt-feed pawl on its

llext movement to the left.

48. Trigger action in automatic fire (figs. 8 and 12).-If

the trigger is held, as the sear moves forward with the bolt,

the trigger cams engage the sear cams and force down the sear,

releasing the firing pin. 'l'lle gun thus fires automatically, re-ll('ating the operations of functioning already described.

SEJCTIO:f VI

STOPPAGES

49. General.-'Vhile immediate action and stoppagt's are

elosply related, the former is treated separately to emphasize

tIle advisability of teaching immediate action as an automaticIlTid distinctive operation without consideration of causes.

h'over care of the gun and attention to the points before, dur-

ing, nnd after firing will greatly reduce the liability to stoppages,

llurticularly if the gunnpr has an intelligent understanding of

the reasons why stoppagps generally occur. Prcrcntion is the

1,c,~t 1'Cl11Cdy for all stoppages.

50. Classes.-Stoppages may be dassell under two mainhl'udings :'

a. 1'cmporary.-Temporary stoppages are caused by-

(1) Failure of some part of the gun of which a duplicate is

earried.

(2.) Faulty ammunition,

(3) Npglect of points before or during firing.

(4) Lack of knowledge of the operation and functioning ofthe gUll.

b. ]'l'olol1gC(Z.-Pl'olonged stollr:nges are causeu by a failure of

folOll1eart that, 3S a rule, ('an not he remedied by the gun squad

U!Hlerfire or without skilled nssistanefl. These nel'essarily put

the gnn ont of netion for a more or less prolonged pericH!.

51. Ullusual malfullctiolls.-a. Rccllrrin!! short 1'ound.'l.-

COl'l"l'CtiOllf this malfullction is IJl'ovideu for in immediate ae-



28 BASIC FIELD MANUAL

tion. In guns In which the parts are badly worn It oecur'l

frequently. Excessive wear of the belt-feed lever 5tud,

feed lever pivot, and front end of the belt-feed lever, or a bent

belt-feed lever, allows lost motion In the action of the belt-feed

lever so that the slide does not force the cartridge fully to theright against the cartridge stops. This permits the left corner

of the extraetor to strike the rim of the cartridge when the

bolt moves forwal'd. The extractor fails to engage the cannelure

of the eartridge and drives the case forwlIrd over the lmllet,making a short round.

(1) Examination of the base of the first cartridge removed

from the belt in immediate action wiII show a dent in the rearend of the ('ase, made by the corner of the extractor. The bullet

Is driven part way into the brass case.

(2) As a temporary remedy, remove the cover-extractor

spring. This will usually allow the extractor to ride up over

and engage the cartridge, At the first opportunity replace tbe

cover-extractor spring and put in a new belt-feed lever andbelt-feed lever pIvot,

(3) The belt feed is correct when the slide protrudes about

one-sixteenth inch beyond the right edge of the cover. If the

edge of the slide is flush with the right edge of the cover, the

gun may function without short 1'0. uuds, but the cartridge is not 1.

against the cartridge stops uule:o;sthe slide protrUdes.

(4) A defective belt-feed lever may be straightened to make it

l,ush the slide fUlly to the right. I'lace it in a vise and carefully

fH}UeeZet to reduce the amount it is bowed or plnce it on edge

with the two ends resting on a hard surface and tap the middle

with a light hammer until the same result is obtained.

(5) The left corner of the extractor may be flIed down by au

experienced mechanIc in Such a ,manner that the extractor will

he cammed over the buse of the cartridge instead of striking it.

b. Dc!cctitVJ triguer.-(l) I!'orward end of trigger sprung'

downward; trigger too short, or beveletl surfaces of trigger and

!'ear burred or worn. ({{nnaway gun.) The gun cun not be

('ontrolled through the trigger. it will fire the moment the bolt

Is home the second time during loading, or, if the defect occurs

during firing, the gun will not stop firing when the trigger br£.le,ased.

(2) To remed.r-

(a) Ket:,p the gnn direcf{\d 011 the target.

belt.



I

i

r

I


(b) Raise the cover and remove the belt. Raising the cover

fltoDf>he firing.

(c) Strip lock frame from the gun.

(d) Examine the trigger and sear and remedy the defect.

c. Broken barrel ea:ten.~~i()JL.-(l) 'l'he bolt will not go homenlld the gun will stop firing". In rare cases the gun will fire a

fl'\V rounds with a brokt'n burrel extension.

(2) To remedy-

(a) When performing immediate action the breakage will be

Ob\"ious.

(r) Strip the groups from the gun and replace broken part.

d. Brolcen T slot.- (1) A broken T slot will fail to extractthe empty case from the ehamber and will usually scar the rim

Of the case.

(2) When glancing into the chamher in the second phase of

hillnediate action, the broken T slot may be seen; or, when

the empty case. is removed with the cleaning rod, the rim will

l(lSllalIy give an indication of the broken part.

e. Loose bullcts.-In some lots of ammunition which have

""Nl in storage for a long time, there is a certain percentage'If ('artridges in which the front end of the case does not hold

th~ bUllet firmly. 'l'he end of the case is usually split where it

gr'iJ)sthe bullet. Such eartridges usuall~' load satisfactorily in

the belt-tilling machine alHI are not noticed. 'Vhen the ex-

fl'uetor withdraws the cartridge from the belt, the case only is

"'ithdrawn, the bullet rpmaining in the lJelt.

(1) Examination of the mechanism of the gun will disclose

'gl'Uins of 100Hepowder in the mechanism and chamber. This

]IOWderusually In'events functioning" of the parts and must be

1'('lllO\"p(}ith the ehamher brush before firing can be resumed.

If the gun is very hot, the powder may fiash and burn the face

,(II' hands of the gunner as he raises the cover.

(2) '1'11ere is no way to prevent this stoppage eXc0pt by

;'J{uminatton of suslwC'ted ammunition, round by round, either

llefore or after it is IOlHl0din the belts. The cartridges should

Ie held and an effort made to pull eaeh bullet from the case

,With the fingers. As this stoppage probahly takes longer to

('leur than any other cHusell by faulty ammunition, and as it

(I('('urs frequently in SOllie lots of ammunition, the importanee

Of eXamina tion of ammunition will be apparent.

~




f. Tight packing.-Too-tlght asbestos packing will give slug'

gish operation and stoppages. MUZZlepacking is more likely to

cause trouble than breech packing. .

52. Classified table of stoppages.-A classified table of usual

stoppages is found. below.' The column headed "Method of

preparation for instmction in immediate action antI stoppag(~s#

should be used for reference only. Throughout instruction ill

usual stoppages the prpscrihed form of immediate action: should

be applied in sequence until the stoppage is -remedied. It will

be impressed upon all thllt the position of the bolt handle is not

to be taken as an indication of the phase of imme(liate actioP

to be applied to remedy a stoppage. This table will serve as II

guide to instruction in the usual stop £luges.

Phase or im-mediate action Stoppage.'l

Method or preparation ror in'struction in immediate actiaDand stoppages

1. Place a dummy cartridge 10,the belt. r

2. Leave an empty loop in tbe,belt.

3. Do not prepare.l4. Drive the front portion or'

cartridge securely on ,dummy cartridge. Pull thebolt to the rear and pl!\()llthe cartridge properly ov!race of the bolt. Ease thet

bolt forward. ,1. Pull a cartridge partlaily

of the belt.2. Place a short round in the belt.~. Insert the front end of a sepa'

rated case in the chamber,and loud. For range put'poses file a line around tbecartridge case about Y2 incblfrom the baso. Be carefUnot to file too far through, asthere is danger of the bullel

staying in the charnbflr.4. Do Dot prepare.1

.~. Insert bulged round in thebelt.

6. no lIot prepare"7. Do not prell:lre"

4. Separated cases due to toomuch head space.!

5. Bulged round.

6. Til:ht loop in tht1 helt.17. Bullet loose in tho cartrid~e

case.!8. Battered or thick rim or

cartridge.

9. Broken canllelure.

8. Place It hattered or a thick'rimmed oortridge in tbebelt.

O. Place a dummy cartridJote

with rim filed on: in tbechamber.

10. Set-back primer.! 10. Do not prepare. I

I Not prepared ror instruction in Iu;.mediate action.

First phase 1. Misfire due to defectiveprimer.

2. Empty loop in belt.

3. Stretched or torn helLI4. Separated case which is re-

moved from the chamber hythe new round when thebolt is pulled to the rear.

Second phase._ 1. Delt improperly loaded.

2. Short round.

3. se8~:~h~~~:-'~~~ht~:b~1ris pulled to the rear.

OUI



-BASIC FIELD MANUAL 31

Phase ofim-lllediate action

StoppagesMethod of preparation for in-struction in immediate actionand stoppages

------1--------------1-------------Second phase... 11. Thin rim. permitting the• nose of the bullet to dropbelow the chamber.!

.ThIrd phase 1. Short or broken firing pin.

2. Weak or broken firing pin-spring.-

3. Faulty engagement of tiringpin and sear notch.

4. Broken sear !'lpring.5. Delt-foed lever pivot out,

worn, or broken.6. Bont or worn belt-feed lever.7. Belt-feed pawl spring out or

woak.8. Delt-feeti pllwl pin out or

partially out.9. Cover-extractor spring out or

weak.

10. Belt-feed lever weak (stud onlever jumps out of earngroove).

11. Damaged extractor.12. Delt-holding pawl out or

spring weak (will cause ro-curring flrst phas!').

13. Broken extractor or ejector.

14. BrokAn or damaged T slot,!

11. Do not prepare.!

1. As,~emble the bolt with adefective tiring pin, or place5 or 6 successive range-. dummy cartridges in thebelt, for instruction in im.mediate action.

2. Same as 1.

3. Assemble the bolt with de-fective parts.

.1. Same as 3.5. Assemble the cover with de-

fective part.fl. Same as 5.7. Remove belt-feed pawl spring.

8. Remove belt-feed pawl pin.

9. Remove cover-extractor spring.

10. Assemble with defectivepart.

11. Same as 10.12. Remove belt-holding pawl.

13. Assemble bolt with defec-tive part.

14. Do not prepaTe.l

------------_ .._-------------------------'-------------

INot prepared for instruction in immediate action.

SJ <X:'!10N YII

TRIPOD MOUNTINGS

53. General.-The weight of the machine gun makeR neces.

~ary the use of some form of fixed mount to support the gun in

firing. 'rhis mount is usually equipped with mechanical devices

by llleans of which the fire of the gun can be suitably controlledIndirection and elevation. In the United States Army the fixed

mount takes the form of u tripod, with the gun carried on a

cradle 80 arranged that it may be rotated about a pivot, per-

lnitting fire in any direction without moving the mount itself.

Changes in elevation are obtained by means of u hand wheel

"'hleh controls a screw attllchc>d to a bracket on the bottom

lllate of the gun near the rear of the receiver. The legs of thetripod are so constructed that they may be mounted at various




heights independentl~' of each other, thus permitting a level

mounting of the gun on sloping amI uneven ground. Three

forms of tripod exist at the present time, the Drowning machine

~un tripod, 1\11917,the mnchine-f.,'Untripod, M1918, and the Mk.IV. The 1\11917 has certain advantagps over. the other tw

types, and will be the one normally issued to troops for use ill

Ileace-t1me training. The Ml918 and Mk. IV are kept in storag

as a war reserve.

7'VN.JJLUI CLAMPING HANDLI!

PIIVTLE

FIGURE 10.-1'11IH7 tripod

54. Description, M1917 tripod (fig. IG).-a. The centrll

member of the tripod consists of the brass socket with thrc

projecting lugs. Serrated front cluteh plates are attached t

the front Jugs. The front legs Lear serrations similar to th

clutch plates and are held 'attached thereto by the front Ie

jamming handles. Th('se handles press against slwing disl{

(saucer-shu{l('d stet'l washeno;) on the outer sille of the legs an

force the serrations into each other, thus positively clampln

the front legs at anJ' deslrell height. The spring llisks prevcn

the vibration in firing from loosening the jamming handles

The rear leg, or trail, is adjusted and clamped in a similu

manner. "'hen the tripod is in use, the rear leg is set at a con

venient height for firing and adjustments in mounting IllIHIeoll

the front legs.




0. The brnss pintle tUs into the soeket and turns in it as a

llivot. The traversing clamp prevents the pintIe from being

Ilulled out of the socket. The ease of rotation of the pintle is

Controlled by the traversing clamp. The traversing dial may

be rotated in its seat and is graduated clockwise in azimuth to

6,400mils, with a 8ma11estreading of 20 mils.

c. The cradle is assembled to the top of the pintIe. Its ver-

tical movpment around the uxis bolt may be adjusted or fixed

at a desired point by means of the elevating arc clamp. Small

changes in elevation are ohtained by turning the elevating hand-

Wheel on the rear of the cradle. A 1-mil click is provided to

assist in regula ting searching fire. A complete turn of the hand-

Wheel makes a change of elevation of 25 mils. The length of

the elevating screw permits a total change of elevation of about

125 mils. A handwheel locking screw is provided. The gun is

l1lounted on the crndle llnd is held attached thereto by the

trunnion and eh~vatlng pins.

SECTION VIII

SPARE PARTS AND ACCESSORIES

55. Accessories and spare parts chest.-The spare--parts

('hest is intended to provide the gun squad with immediate

l'eplacement of serviceable parts for those which become defec-

tive In the gun in use. It should, therefore, be kept completeat all times with its contents in good condition. Parts carried

('omplete, such llS the spare bolt, should at all times be correctly

assembled and ready for immediate insertion in the gun. All

sPare parts should be kept clean and lightly oiled to prevent

l'U81. Smaller parts should be kept in the fabric envelopes or

Containers to prevent loss.

56. Spare barrels.-When spare barrels have been zeroed,they should then be well covered with rust-preventive compounds

Us if being preparell for storage and kept in the spare-barrel

covers. Spare barrels should never be carried or kept exposed

to the aceumulntion of dirt, sand, and moisture. As a general

rUle only oIle harrel should be in a('Uve use in the gun as long

flS it remains serviceable, the spare barrels being kept as a

l'eserve suPVly. Spare barrels should be occasionally cleanedof rust-preventive compound and inspt'Cted to be sure that they

l'Pllillin in good condition.




57. Belt filling machine.-a. Gcneral.-The belt filling ma'

chine is uesigned for the rapid loading of belts anu is intended

to be screwed to a table, box, or other solid base when in use.

A wooden box is provided in which to IlllCk the machine wheDnot in use. The interior of the box is provided with compart-

ments and bl()(:ks for the cartridge guide and the frame with

its assembled parts. Care should be taken that the machine is

properly paeked in tile hox and 8ee11rellwith the bloek to preventdamage in trans!lorta Uon.

, b. Di,'wH..u~mbling and as.'1ctnbling.-The disnssembling and as-

sembling should not be difficult and should require little expla-nation.

(1) To dhJas8cmblc._ (a) Remove the cartridge guide.

(b) H('move the magnzlne by unscrewing the magazine l'lcrewS

. , (c) Hemove the frame cap by unscrewing the frame-cupscrews.

(d) Remove the npedle-bar lever spring by unscrewing It

from the needle-bar lever.

(e) Remove the nppdle-bar lever from the needle-bar leverpin.

(f) Remove the needle-bar slide and separate the needle bars

llnd needle-bar Blide by removing the needlt.'-bur screws.

(g) Hemove the ('arrier spring.

(k) Hemove the slide and separate the slide connection andtile slide.

(i) Hemove the other fllll'tS in a similar manner by raising

~hem from their pins or by first removing their respectiveretaining bcrews.

(j) Do not remove the belt-guide screws.

(2) To asscmblc.-Assemble the machine in the reverse orderin which it was disassemblf'd.

c. Adjustment before use.-(l) See that the hearing surfaceH

nnd moving parts are well oiled.

(2) ~ee that the net~dll's are properly 8et with each upper

needle din'dly above the cOl'l'esponuing lower needle and that

tile"points of each upper Ilet'dle are even horizontally.

(3) See that the points of the upper needles are about 0.01

inch ve'rtfcally above the points of the lower ne(~dles. A play-

ing card mnkes a convenient gauge for r('gulllting the distance

hetween the upper and lower needles. In tilling helts the needles

sometimes fail to pkk up the belt and op(\n the loops. The



BARIC FIELD MANUAL 35

remedy will usually be effected by settin~ the upper and lower

needles farther apart.

(4) See that all screws on the maehine are tight, particularly

the slid('-('onneetion screw.

d. O(icration.-(l) To fill a belt with cartridges, screw the

lUaehine to a table or box with some support to catch the loaded

end of the belt f;O that it ean not hang more than a foot below

the maehine. The weight of more than one foot will pull the

helt improperly through the feed wheel.

(2) Helease the tension spring and raise the upper feed wheel

as far as it will go.(3) 'l'urn the lIelt-g-uide eoyer to the rig-ht far enough to ad.

111it the lIeIt into the belt guide and raise the upper needle bar

as far as it will go.(4) Plaee eartridges into the guide, either out of boxes or

clips, and turn erank to the right until the first cartridge has

heen pUl--hedforward with bUll~t extending past lower nef>dle

har.

(5) The IIlaek thread indicates the side of the belt for en-

tranee of the cartri<lges. Put a eartridge by hand into the

loop of the belt nearest the brass tip so that one-fourth inch of

the brass end of the 'shell near the bullet sticks through the belt.

(0) Place the b('lt in the machine so that the cartridg(> in

the belt l"Psts in top groove of lower fped whef>l with IlPad of

('flrtridge vressed against regulator spring. Start the bullet of

the secow] eartri<lge, which was fpd out by turning the crank,

Well into the second loop of belt and place helt in belt guide.

"I'urn tlw belt-guide ('over to the left to hold down the belt.

Lower the upp('r nee<lle hare

(7) Turn the upppr-fped whepl down upon the belt an<1secure

the tension sJlrin~ under the hook. On some models the hook

has two notdles so that the tension can be varied. When load-ing new belts, or belts which have 1)('en tightellPd by dampness

or other climatic cOn<litions, the lower noteh should be used so

that the belt is held more firmly in the feed wheels and car-

tri<lges are force<] in the pro)lf'r <1istan('e. 'Vith ordinar~' belts

in whieh the ellrtridges do not enter into the loops with exees-

Rive difficulty, the upper notch is used to give less tension.

\VII(>nthis not('h is 11S('<1, the machine works easier and there isless tendency for the belts to wear out.



3GBASIC FIELD MANUAL

(8) Turn the crank to the right and cartridges will be fed

into the belt ready for use in the gun. To insure loading Witb'j

out empt~' loops in l.x>lt,the crank must not be turned faster

than eartrhIges are fed to the machine, and care must beexercised to insure that cartridges do not stiek in the gui~e.

LightlJ" oiling the surfaces of the guide which engage the rlJ)1

of the cartridge will usually make the machine feed smoothly.

c. Adjustment during use.-(l) See that the cartridges fall

und lle evenly in the cartridge guide and that the machine doeSnot get ahead of the SUpply of cartridges.

(2) See that the belt enters the bl'lt guille properly and doeSnot become twistell, and that the weight of 110tmore than onefoot of filled belt hangs from the machine.

(3) ShoullI a miss occur in loading, stop and remove the belt,

turn the crunk to "Position" a cartridge over the lower npedle

bar as in starting, replace the belt with last cartridge in th~

top groove of the lower feelI Wheel, close the machine, and pro-

('eed. Misses are usually caused by a duli, broken, or improp-

erly adjusted needle, or loose screw on SOUle part of the

machine. In some cases the machine will start to load properly,

but the belt wiII slip to the right between the feed wheels, giv-

ing uneven loading with successive curtridges, until finally the

belt is too fur to the right for the needles to pick it up and open

a loop. This Usually occurs with machines Which have a single

notch in the tension-spring hook, anll'is caused by insufficient

tension on the tension sllring. To remedy, place a splinter, car.

trldge clip, or other object between the hook and the end of the

spring to increase tension. To remedy permanently, loosen or

remove the tension-r-prlng screw and place a svlinter or small

roll of paper unuer the spring outside the serew in such a, wuy

that when the screw Is tightenell the outer end of the svring

will be raised and thus increase the tension When it is engaged

under the hook.

(4) ShOUld a jam OCCurin loatling, stop turning at once.

Block the cartrlUges in the guide, ,remove the belt and thejammed cartrillge, unu proceed a8 In (3) above.

(5) If difficulty is experienced in loading new belts, loops

may be preViously stretched. For this purpose a small stick

may be rounded and tapered on one end to the size and shape

of the cartridge. This sharler is then successively inserted 1n

each loop from the black-threaded edge. To avoid excessive




8tretching, the shapero should not be larger than the service

cartridge.

58. Blank ammunition attachments.-a,.The blank .ammu-

nition attachments for use with the Browning machine gun

have been developed in order to simulate fire. The attachments

are designed to fire l\f1900 ammunition and consist of-

Muzzle attachment, assembled:

Muzzle-attachment gland.

Muzzle-attachment plug.

Muzzle-attachment cap.Cartridge-stop attachment.

FIGURE 17.-Blank ammunition attachments

(1) The 'ttluzzlq (Jttachm~nt is assembled to the gun by

removing the muzzle gland and, with the packing in place,

81111inghe muzzle-gland end of the assembled attachment over

the muzzle of the barrel and screwing it into the end cap with

the combination wrench.

(2) The cartridge-stop attachment is inserted by withdraw-

ing the belt-holding pawl split pin about one-half inch, and

f!llding the attachment over the cartridge stop, lining up the

Small hole with the belt-holding pawl split pin and replacing

this pin. The cartridge-stop attachment acts as a guide for the

blank cartridge and also as a cartridge stop. Its chief use is

to hold the cartridge in position in feedway so that the extrac-

tor may engage Its cannelure, and it also prevents the entranceof a live round foto the feedway.

b. Precautions.-(l) Never attempt to use the muzzle at-

tn(~hment unless the cartridge-stop attachment is in its proper

tJlace in the feedway.



38BASIC FIF.LD MANUAL

(2) See that the mUZZleattadlInent i,<.; clpanf'd inside hefo!'using.

(3) .After firing hlauk Ilmmunition, clean the hanel and muZ

zle attaehmf'nt. It is absolutely esspntinl that this be don

before firing any other type of ammunition.

(4) It is well to use old barrels when firfni: blank ammun!

tion.



CHAPTER 2

MACIIINH GUN MARKSMANSHIPParagraphs

SECTI ON I. General______________________________________ 59-62II. Prpparatory exerci~;es __ .. 63-74

III. Course to be fired______________________________ 75-76IV. Conduct of range {l1'llctlce __ :-___________________ 77-99

V. Rules governing record practice :.. 10(}-115

VI. Construction of targf'ts, ranges, and equipment , 116-119

VII. Advice to instructol's-------------------------- 12(}-126

SECTION I

GENEUAL

59. Scope.-This ('hapter prescribes courses of instruction,

rUles, and regulations apvlicable to ..the general subject 'Of

1llachine-gun marksmanship, the purpose of which is to train

1llen iIlllividually to b~ome good shots.

60. Fundamentals.-n. rI'o become a good muchine-gun shot

the soldier must be thoroug-hly trained in the following funda-

1llentals of machine-gun marksmanship:

(1) The accurate delivery of the initial burst of fire.

(2) Mechanical skill in manipulating the gun to obtain

Droper distribution of fire over turgets requiring distributiOll.

(3) OhsNvation of fire and the adjustment of fire from

ob!'lervation.

(4) Speetl in eombilling the above-mentioned three elements

in delivering fire.

b. All of the preparatory exereises and the range-practice

exel'cfs~ prescribed in this ehapter are for the purpose of

truinlng the soldier in the four fundamental elements enumer-

nh'd nbove. 'l'hroughout the period of training in marksmanship

the in~tructor will emphasize the importanee of these funda-

lnentals.

c. Mathine-gun tiring is a meehanieal operation which any-

one Who is physieaUy awl mentally fit to be a soldier can learn

to do well if properly instructed. The gun is a machine which

teacts in direct proportion to the mechanical skill with which

39

'




It Is operated. Before men are permitted to fire the gun theY

must lte thoroughly instructed and drilled in the mechanism of

correct firing. 'rhey must be prollerly coached when they begiJ1

firing, otherwise they will instinctively commit. errors, such a!l"riding" the gun, and thus begin the development of faultYhabits.

61. Methods of instruction.--ci. Machine-gun marksmanshiP

instruction is divided into two phase!'!, preparatory training and

range practice. Range practice is divided into instruction, pre-liminary, and record practice.

b. The sequence of instruction throughout will consist of all

explanation of eaeh step accompanied by a demonstration andfollowed by practical work.

o. The offieer in direct charge of the conduct of the training

will act as instructor; he will give the explanation of the exer-

cises to be undertaken to the assembled unit. The explanation

for the first four steps in the preparatory exercises will include

a demonstru Hon of the work being taken up. This demonstra-tion should be Performed by a squad which the instructor haS

trained in the exercises which constitute the day's work.

explains llOW each of the exercises about to be taken up is

why it is done, and its application to machine-gun marksmanl~

ship. These talks and demonstrations are an essential part 0

the training; they should awaken interest and enthusiasm for

the work and give an exact knowledge of how eaeh step is tobe carried on; things that men can not get from reading a de~

R('riptlon, no matter how detailed and accurate that descrlptioU

1ay be. The instructor may be the platoon leader giving these1talks and demonstrations to his platoon, the company com-.

mander to his comp:llly, or a specially selected officer to a group

of ma('hine-~n companies. The number of men who can be:

taught to shoot at one time by a good instructor is limited onlyto those who can hear his voice and see the demonstration.

d. Upon the completion of the explanation and demonstrn}

tlon by the instructor, in which the exact manner of conducting

the exercise is ('Overed in detail, the assistant instructors carry

out the practical work phase of the l';equence of instruction:

under his 8upervh;ion. ASSistant instructors are the lenders of

8uhordinate units. A squad is the largest unit in which careful'fnllh.idual instruction can he closely supervised. For the first

fonr stepo In the preparatory exercises the squad instruelor]

IIe

done,



!

!


Will perform duties as prescribed in Section II. It is an advan-

tage to have the assistant instructors trained in fidvance, but

It Is not essential where armies are being hastily organized

Und time is not available. When one instructor is conducting~Uceessive organizations through machine-gun practice, it is

fldvisable to attach to the first organization taking the course

officers and noncommissioned officers of the companies that are

to follow for the period of preparatory training and for a few

dayS of range practice. These act as assistant instructors

WhentheIr own companies take up the work.

e. The instruction must be thorough and individual. Eachlllan must be brought to as high a state of proficiency on all ofthe enumerated points as the time allowed. for preparatory work

\\'ill permit. The importance of exactness must be impressed on

the men at all times. For example, men in adjusting the sights

1n the sighting and aiming exercises are apt to say, "That is

about right." There is no such thing as a sight that is about

l'ight; it is absolutely right or it is all wrong. Exactness inevery detail is hard to get, but it must be attempted.

f. Under the coach and pupil method the men undergoing in-struction are grouped in paIrs and take turns in coaching each

other. The man undergoing instruction is called the pupil;

the man giving instruction is called the coach. When the men

,of a pair change places the pupil becomes the coach and. the

Coachbecomes the pupil. The assistant instructors, particularlyISqUad.nstructors, supervise and prompt the men who are acting

IllS coaches. This method. of instruction is particularly appli-

I ('able to the first sighting-an d.-aiming exercise where several!3ightinghal'S should he utilized to speed progress in instruction.

62. Prior training.-The soldier must be proficient in me-

Chanical training and in the prescribed. tests of elementary

training (Basic }"'ield Manual, Vol. II) before he receives in-struction in machine-gull marksmanship.

SECTION II

PREPARATORY EXERCISES

63. General.-a. The purpose of preparatory exercises is to

teuch the soId.ier the correct way to do each of the fundamentals,

and then to drill him in correct methods so that they become

fi:lCedhabits before he undertakes range practice. Time and

llnlnlUnltloll will be greatly conserved during range practice by

980:;3°-32--4




ehndueting a thorough, carefully supervised course in the pr

llal'a tory {'xcrcises. .

b, The preparatory exercise:o;consist of five distinct steps al

8houhl he given in a coneentratelI period of time, They induthe follow! ng: Inl

Sightlng-and-aiming exercises.

Position exercise. !'iii,

Sight-setting and laying exercises,

Manipulation exercises. .'

Examination of men before starting r~nge practice. Illl

c.The blank form shown in paragravh 74.

w'mhe kept

each platoon lealieI'. Each man will be put through a thoroU tilt

test along the lines indicated before he is allowed to tire a sb

a. Evpry IlIan who is to fire on the range, indwling tho

who have prpviousl~' qualitlcII, will be put through the prepuJ nltory ('ourse from the beginning.

. 64. Duties of leaders.-a. Platoon leaders act a:o;assi:o;W1\

in8tructors, organizing and sUlwrvising the instruction witIl

th{.ir platoons. They will exaIlliIl(~ anlI rate each solUierloprps('rihpIl in llara~ruvh '14 wlH'n (~ach phase of prevarato h

training is eompletpd.

b. Sp('tion leaders supervise the instruction within III

se('Uons.

c. The squad leader performs the following duties:

(1) Organ1zps 01{ work within his squad.

(2) Performs the duties prescrihctl for the squall instrud

(3) SeeR that the machine-gun (>quipment assigned him

kept e1pan, rel1aired, and adjusted.

65. Equipment for each squad.-a. The equipment requi

for the exercises is as follows: Ih

(1) Four 1'1ghtlng bars comvlete. O'ig. 18.)

(2) One 3-10('b sighting target. (Fig. In.)

(3) One frame, 3 feet by 5 feet, eovered with blank paP h

anll bral'CII for mounting on the ground, to be used in makitriangles.

(4) One mnni[IUlatlon target. (~"'jg.'23.)

(5) One each of machine-gun targets A, n, a, D, and(Fi~. 24, 25, 2G,27, 28.)

(G) Material for blackening sights.

(7) Pencils.(8) T18sue paller for c01.lying triangles.

u

th

e

1

h

I

I

1

h




(9) One machine-gun and trivod.

(10) Three sandbags.

J. '.rhe equivment should be carefully inspected for accuracy

Ii servic(~ability before it is used. It should be carefully

de, accurate, and serviceable.

. The sighting bar and sighting target are constructetl as

)Wn in I<"'igures 18 and 19.

36. First sighting-and-aiming exercise.-a. The purpose of

first sighting-and-aiming exereise is to teach the correct

g'llment of the sights on a target.

J. For this exercise the instructor shows a ~ighting bar to

groups, indicates ench part, aTHl explain:o; its use as follows:

(1) The ~dghting bar is used because it assists in easily de-

ting small errors and explaining them to the man undergoing

;truc1ion.

(2) The front and rear sights on the sighting bi1l' represent

urged machine-gUll Sights.-

(3) '1'he e~'epiece causes tlw solilier to place his eye in such a

~ition that he sees the sights in exactly the same alignment as

~y are ohserved by the instructor; there is no e~'eIJiece 011 the

lChine-gun, but the soldier learns by the use of the sighting

l' how to nlign his sights properly when using the gUll.

(4) The attadunent of the removahle target to the ('nd of

the sighting bar provides a simple method of readily alignin,~

sights on the target.

'. The iJ1l';/ruetor then explains the peep sight to the assem-

!(} groulls, showing them tIle illustrations of a eorrect sight

g'nment. (Jj"'ig. 20.)

t. T1,l.e };IJuads re/unl to tIH'ir ~quillm~llt where the squad

tl'uctor conduets. the followillg eXl>rei~l'S :

(1) lIe dl'seribes a corrednim, showing' Figure 20 to ellell

In. lIe eX[llains tha t the tf)}}of tIle front sight is seen through

milldle of the circle, and that it just touches the bottom of

target HI) tliat all of the target can be ell'arly seen.

(2) Ileexplaills that the eye should he focused on the target

aiming, and he assures himself, by questioning, that eaeb

dier unl1l'rstllnlls what is meant' by f()('using the 'eye.

(3) lIe s() adjusts the sights of tIle sigbting bar and the mov-

Ie target liS to illustrate a correct aim and has elleh man ofgroup look through the e~'evie('e to observe this correct aim.



44 BASIC FIF..LD MANUAL

General View

TOPVIE.W

2001" 1<

SIDE. VIEW

G'l9htul9 Tar-gst Peep .5l~ht

(of (b)

front.5t.sht Open 5lght

foldedl'shape Sil(~ Accessories

2.2"

1~3~ k-3~

[,/0<"',-1~~t,ece

Fold on dotted lU\e~

$0,

I'I

HOlerfromtop center

I

jin center %0';

HInck bull'S'

FIGURE l8.-The BI~ht1nl{ bar

Construction"'ooden har-1" x 2" x 4' (approximately).It;yepiN'e-Thin metal 3" x 7"-11011' .O:J" dlamph'r.Rear 8lght-Thin metal or cnrdhonrd. 3" x 3" holediameter.

It'ront Hight-Thin metal Ih" x 3" lJent .. L" shape.TarJ{et-'l'hln metal or cnrtlboard 3" x 3" painted white.eye %" c1hlmetl'r in cent" ...

~lIt_l" det-p, may be lined with thin metal HtrlpH.

24"

1

FIGt:'RE In.-The sighting targpt

~

~

~



BASIO FIELD l\fANUAL 45

(4) He so adjusts the sights and the movable target of the.

,~i~htingbar, as to illustrate various small errors, and has each

I

tnan of the group attempt to detect them." . .

67. Second sighting-and-aiming exercise.-a. The purposeof the ~econd sighting-and-aiming exercise is to apply the pre-"

,(~ellingesson to the actual alignment of the machine-gun sights'

on n target.

b. (1) A machine gun with sights black-

(~tH~ll is mounted in the lowest position

lind {lointed 11 t a blank target placed 100

~.UI'ds from the gun.t (2) TIle instructor takes a prone posi-

Ion at the gun with no part of his body

~U[)llortedby the gun or mount, his chin

l'e~tingon the palms of his hands, with his

('!Lows on the ground or on a sandbag FIGURE 20 . ....:-Correct

lit alignment of sightsted over the trail, so that the eye "is in. .on aiming paster

he ('orrect position for aiming. (Fig. 21.)

(:l) A man is posted near the gun to transmit signals to the

Iltker. 'l'he marker, provided with a 3-inch sighting target,

ak(>!ol his plnce" at the target. The instructor, by improvised

IOD-YDS-

-" -~

FIGURE 21.-Shot group exercise

l.(llllis transmitted through the man posted near the gun, di-

(~%!the marker to move the sighting target until it is in cor-

~('t alignment with the sights, and then commands: HOLD.

he marker complies, holding the sighting target in place onIe target.

(~) The instructor then explains tha t each soldier wiII look't(Jugh the sights of the machine gun at his own squad posi-

OIl, and in addition will be required to deteet and correct small

rOts in aiming.




c. The !'quads return to their equipment, whereupon eae

~f1uad instructor carries out the following exercises:

(1) He performs the exercise described above to secure a

red sight alignment and requires ench member of the squad

look through the sights. .

(2) The squad instructor direct:" the marker to movesighting target slightly out of alignment. Eaeh soldier unde

goiIig instruction then takes position at the gun and direc

the marker to move the sighting target until it is in corr

alignment with tIle sights. The squall instructor .eheCks tb

alignment in each case. .

. (3) Where extra machine guns are available the

described in (2) above can he greatly facilitated by requirln

its completion by the coaeh and llupil method.

68. Third sighting-and-aiming exercise.-a.The purpose

the third ~;ighting-awl-uiming exereise is to show the

(If uniform fin<l coned aiming, awl to instill into the mind

the soldier a sense of exactness. .,. .' I, •

b. The instruetor explains the Imvortance of exact and un

form aiming and demonstrates the following exercise: rf

machine gun, with the sights blackened, is mounted in the

r.ositlon and I)ointed at a blank target llhl('ed 100 ).a1'd8 from t1gun position. A !mlilier takes the position described In the

uncI sighting-and-aiming exereise and looks through the slgll

(Fig. 21.) lIe dlreets the marl~er to move the sighting targun'tll it is in correct alignull'nt with the sights, amI-Uue'll

mand,s: HOLD •. The marker complies, us heretofore explain~

The instrut.tor then looks through the sights to see.1f the ali~

ment'ls ('OlTeetor incorrect; thereafter, without.sa;ying anythif

to the soldier, he commands: MARK. The nutrker, without roO

fng the sighting target, makes a dot on the paper with a shal

Ilointed penca in~erted througl~ the hole in the center ofsighting target. Ill' llumhers this mark" 1." The marker

moves the sighting target to change the alignment •. The

und instructor, without touchln~ the gun or mountt repeat t

operation until three dots have IlPeh registere<l, numbered 1,

nnd 3, respectiYely. The instruetor 110W discusse~ with the

dier any errors of sight alignment and the probable shupe'

the shot group formed by joining the three dots .. Themar~traces the three dots on the tissue paper with which he is i

nished, joins the three points to .make a' shot group, writes

C

t~

eXerCl

ill1portan

lowe

s

co

th

soldl



f

BASIC l"'IELD l\IANUAL 47

E!Oldier'snnme at the bottom, anI] transmits the paper to the in-

£Itruetor. The size and shape of the shot group will then be

tlllicUssed and the errors pointed out. At 100 yards with the

a-Inch sighting target a man should be able to plaee all three

lnarks 80 that they can be inclosed in a eircle 1 inch in diameter.

O. The squads return to their equipment, whereupon the squad

II¥-itruetorrequires each man to perform the exercise describedIn b above. . ..

I d. One gun for each four men will facilitate instruction, be-

Icause each man can then be nssigned duties as shown in Figure21. Squad instructors should rota te the men under instruction

I

&ft('f the completion of the exercise. Each shot group will be

UiI,;cussedwith the soldier by the squad instructor. All shot

groups will then be turned over to the instructor. This exercise

"'1I1 be rer~atedulltil proficiency is attained. .

69. Fourth sighting-and-aimingexercise.-a. The purpose

Of the fourth sighting-and-aiming exercise is to demonstrate the

l!t'fl~tof canting the gun, an error which is caused by mounting

the tripod 80 that the traversing dial is not level.

b. The instructor, explains that if the gun be canted to the

l'lgilt, the bullet will strike' to the right and below the point

&Illledat, even though the gun be otherwise correctly aimed antI

~he sights ('orrectly set. Similarly, if the. gun be canted to the

(1ft, the bullet will strike to the left antI low.

c, The' men return to their equipment where the squad in-

E!trUctormounts the gun with the dial inclined; he then requires

~ll('hsoltIier to point out the error and its effects and to make

tho corrections necessary to cause the traversing dial to be

lOl'lzontal.

'70. Position exercise.-a. The purpose of the position exer-

Ille is to teach the gunner to take the correct position at the

Un. The gunner must be able to lay the gun and fire it without

l1"'cting the laying; this requires the gunner to take a position

'UC'hhat no part of his body is supported by the gun or tripoo.

b. The instructor explains ftnd demonstrates the normal sitting

Oliltion, the details of which are as follows (fig. 22) :

(l) The' gunner sits in rear of the tral1 shoe, straddling the

ran, with tlle feet under the tripod.

(2) The knees are (lrawn up and turned out, and the elbows

re supported on the inner surfaces of the thighs.

-



I


(3) The thumb of either hand i:'l phl<'ed in rear of the sto ;1

with the forefiuger on the trigger, the remaining fingers JI

touching the gun. This is the most important part of the

sition; it is tak{'n sol('ly for the Plll'llose of pressing the t1'i

ger properly and not to overcome the natural vibration of tgun or looseness in the mount.

(4) The other hand i~ held opposite the side plate, ready e

tap.

(5) The helHI is erect and the e~Yesare directed toward ttarget.

FIOURE 22.-Correct position of the gunner

c. Each squad then performs the exercise under the suPvIsIon of the squad instructor, who takes position on the 1'1

ot the gun and r('quires .the soldier to explain and demonstrllthe position In all its details.

71. Sight-setting exercise.-a. Tile purpose of the sig

setting exercise is to teach the nse of the rear sight and

den-lop aceuracy and sllecd in. its use. ,

b. The instructor explains how the sight slide is set at t

desir('d range graduation on the sight l<'af so that the g

will havE"the p!"Operelevation when it is aimed. lie expla

that the wind gauge Is graduated in mils, that moving the III

able base of the sight to the right through one grllduation

the Windage scale, and then rplaying the gun, will mo\ e

point of strike 1 mil to the right at the target. The instr

1




)r then has a man take his place at the gun and demonstrates

Ie exercise as follows:

(1) The instructor announces a range and a deflection; for

tUtnple, Range 900, sight right 4.(2) The gunner sets the lower edges of the sight adjust-

lent plate at the range announced and turns the windage

'rew until the index is set at right 4. He then resumes the

()rrnal !>osition.

(3) The instructor checks the setting of the slide and the

Ind gauge.

1 2

• 8-xI

I

10.I,I

.:5 4 5 6 : 7

• ,. I!I " • " !-~<_. 1" •r----1O-- ---'if- - --10- ----~f---.l0-----1T-r-- 0----1

I

1?",8 g :

• II.J

1~IGURE23.":-Mnnipulatioll target

c. Each squad then performs the exercise explained above

Ill.1prthe supervision of the squad instructor until aU are

l'ofieient in rapid and aecurate sight setting.

d. !,'or all sight-setting exerC'ises, the lower edges of the

~'!(l(~Sof the rear-sight adjusting plate will be used in setting

fiE! rear sight, ini"tead of the hori7..ontal line at the peep. The

!'ulolon.or this is diseussed in llaragraph 83.

72. Sight-setting and laying exercise.-a. The purpose of

II(! sight-setting and laying exercise is to develop speed and

('uracy in setting the sights and la~Tingthe gun on an aiming(lint,

1), The manipulation target shown In Figure 23 is set up

flOO inches from the gun (measured from the pintle); the

/I Is mounted for the normal sitting position.

c. The instructor 1llaces a man at the gun to demollstra te

(! exereise as follows:



50 BASIC }'IELI) MANUAL

(1) The instructor announces tile range' and designates the

target by giviIlg a commalll} similar to the following: 1. Rangl,

800, sight right 3, 2. PASTER NUMBER 5. After giving the firsl

clemen t of the COIIIJWllId, the instructor VHuses a sufIicieutlength of time to permit the gunner to l'('veat it. The gunner

then rabes the sight It'a f llnd sets the sight. 'Vhile he 15

setting the sight the imitructor lllllluun('es the target. Tbe

gunuer n'ppats tllis second e]('mt'ut of tile ('omnlaIHI, am! upo!l

eompleting tile sight setting maniVu]aies the gUll, first bY

traversirlg, then by eleva ting or deVJ'('ssing, until tile sightS

are accllrHtely aligll\'<1 Upon the <1esignHtetl aiming voint. lICtllPn takes the tiring position am! calls" Up."

(2) The Instnu:tor then checks the si;.!;1lt setting and laying,

pointing out the e1'1'ors, if any.

d. 'l'he men then go t hrough tJll~ exel'<.'ise under tllt' super'

vision of the squad Inst l'Uelors until they become proficieut

in setting the sight and la~'ing: the gun Oil a designated aiming

}loint within a t.ime limit of ten s('('.on<1s. Each exercise w.start with the sight leaf down awl tlw slide 8('t at 700. Rallgc~

of less thall 500 or greater than 1,--100~h.OUld .1Iot be aunounced'i

c. It lllUst he understood by the soldier that in aiming ut

his target the ('enter of the bottom of t he uimll1~ vaster i~ usco

liS the almin~ {Joint.

{. In the sight-sptting and laying f'xerdse the uuties uf tllC

('ouch are LIS follows:

(1) lIe sees that the proper llosition is maintained at tIlel

gun, paying particular Ilttt'ntion to the hold uspd hy thl"gu III1('1'.

(2) lIe watches the 1IIanipUlation of the gun by the gunner

to see tlmt if is uone cOrJ'ettly, smoothly, ant! without hesitw

tion.

(3) IIe (:hpcks the skht settill~ line} the laying lit tile COllI'

plction of the eXl'l'ehe.

(4) IIe noh's the time uSPel hy the gUllner in the exercise,

73. Manipulation exercises.-,-a. Scarcliillf!.-(1) The pur'

{lose of thl' sl'al'('hillg eXPI'<'ise is to e}l'velov a<:cunl(,~' and Slll'cd

in manipulating the gUll to cover n targpt too Ul'<'V to be in'

cludl'(} in the hpl1t('n zone of H single hurst.

(2) The gun is mounted ill the lIol'lJlal fll'ill~ position and

pointed at a manipUlation target 1,000 iuehes in front of the

gUll position.

il



BASIC FIELD MAXUAL 51

(3) The instruetor assembles the group and explains that

the target is plaeed 1,000 inches from the g,Ullso that a change

of 1 mil in elevation at the gun :will change the point of aim

On the target 1 ineh. Sinee pasters No. 1 to ~o. 8 are 20

inches apart on manipulation target, 10 bursts, eaeh followed by

a 2-mil senrch, will be necessary to cover the target they rep-~esent. The change of 2 mils is made after each burst so

thut the shot groups will overlap, covering the target uni-'

fOrlllly throughout, thus incrensing the depth of the beatt'n

~one of a series of bursts by mechankal weans. The instruc-

tor explains that ('nch click of the handwheel represents 1 mil.

(4) The instructor then has a soldier take his place at the

gUn to demonstrate the exercise as follows:

(a) The instructor announces the runge, aiming point, and

the direction and amount of search. l~xample: Range 800,

Paster No. S, search up 20. 'Vhen the gun is properly laid, he

(:Otnmands: COMMENCE FIRING.

(b) The gunner repeats the commands, sets the sight, la~'s

on the designated aiming paster, and announces, "Up." At

the ('omma11l1COMMENCE FIRING, he simulates tIle firing of a

burst. lIe manipulates the elevntlng handwheel, elevates the

~1I1l 2 mils, and simulates the firing of a burst. lie continues

thl!'!operation until he has made 10 searches of mils each.

bUrlng the exercise he watelles the target and does not look

at the gun or through the sights.(c) At the completion of the exercise the gunner looks

thl'oUgh the sights to see if the total search requireu bas been

correctly pprfornwd and if the line of aim is on paster No.1.

(d) The instructor eaUs attention to each operation as it

ili Ilcrformed by the gunner. At the completion of the exercise

the instructor cheeks the aim and points out any errors that

\V(~remade.

(5) Eaeh squad then performs tile cxerei~e described abo~e

llnu(>r the supervision of the squad instructor until all are

lil'oficient in manipuilltin~ the gun in sean'hing.

(6) During all exercises in lIlanipulation described in this

r1llrngrallh, the men should take the positions and perform the

dUties prescrilwd in Basic Field Manual, Volume II. Ol1(~

Illan ro;houldact as ('o:1eh and perform the dutie~ prescribed

ill d helow. Two guns per squad can lJe used to advantage

In aU of the manirmlation exerdses.

~



BASIC FIELD MANUAL52

b. Traversing._(l) The purpose of the traversing exercise

is to develop accuracy and speed in manipulating a gun to

cover a target too wide to be inclUded in. the beaten zone ofa single burst.

(2) The gun is lllounted in the normal firing position and

pointed at a manipulation target 1,000 inches in front of thegun POSition.

(3) The Instructor assembles the group and explains that

this exer('ise h.l executed in a manner sImilar' to the sparching'

exercise excppt that a 2-mil lateral change in direction is made

nftpr each burst, thus Increasing the width of the beaten

of n series of bursts by mechanical means. He ~xplains that

the 2-mB traverse is made by one firm tap from the heel of:

the hand on the rear part of the side plate after each burst,

the elbow remaining on the inner side of the knee, the force

expended in tnpVing remaining constant. The traversin~'

('lamp will be tHljustpd so that the tap will reRult in moving

the gun laterally through 2 mils. Since pasters Nos. 1 and

2 are 20 inches. apart he eXvlains that 10 bursts, each fol.

lowed by a 2-nlil tap, are necessary to distribute the fire uni.

fonnly over the target. Tapping is the most difficult part of I

manipulation; hence ample practice must be given each man,

with constant stress laid upon adjusting the traversing clamp'to a tap that is strong and unifurm.

(4) If the organization is ('quipped. with the M1918 tripod,

the traversing exercise will be carried. out in a similar mannerj

except that n 2-mil turn of the traversing hand.wheel will be

practiced. instead of the 2-mil tap. It will be explained that

each click of the traversing hanuwheel represents a traverse

of 1 mn, and thpt uniform traversing is obtained by a succes-

sion of 2-mil turns. The traversing Worm gear must be ad.

justed so that it turns with freedom but without excessiveplay.

(5) The instructor then has a man Who has been instructed

previous!>- in the exercis~ take his place at the gun to df'mon-strate the exercise as follows:

(a) The man adjusts the traver~;fng clamp to his tap.

(b) The instructor gives n fire order involving a traverse.

Examp!e: Range 800, paster No.1, traverse right 20. When thegun is properly laid, he commands: COMMENCE FlR/NG.

(c) The gunner repeats the t'ommancJ, sets the sight, lays on

the clesignatell aIming paster nnd aUlIouuees, "Up." At the

zone

.

'



I


~onllnand, Commence firing, he simulates the firing of a burst

, -Ie then taps the gun once in the required direction and simu-

lutes the firing of another burst. He continues this operation

lIntlI he has made ten 2-mil traverses. During the exercise he

\\'utehes the target and does not look at the gun or throughthe sIghts ..

(d) At the completion of the exercise the gunner looks

through the sights to see if the total traverse required has been

~Ol'rectlyperformed and if the line of aim is on paster No.2.

(e) At the completion of the exercise the instructor checksthe aim and points out any errors that were made.

(0) Each squad then performs the exercise described above,

IJraCtlcing traversing from left to right and from right to left

llntlI all are proficient in manipulating the gun in traversing.

J\.fter each man finishes a traverse he must be required to

looRenthe traversing clamp to force tlle next man to adjust it

to tile force of hisOW11

tap. Since tlJe tap traverse is used"'Ith the 1\11917 tripod, it will be impossible always to get an

eXact 2-mil traverse. In any exerci:-;e involving a traverse of

20 Inils, the final point of aim should be within 2 mils (10 per

(lent of the distance traversed) of the correct point of aim in

ol'der to demonstrate proficiency in tapping.

C. Combined searohinf! and traversing.-(1) The purpose of

the Combined searching and traversing exercise is to developUceuracy and speed in manipulating the gun to cover an obliqueturg(.t.

(2) The Instructor assembles the group and explains that

this exerci:-;e combines traversing with searching to cover a.

tUrg(~trepresented by pastel's Nos. 8 and 2. In ('overing such

U target a 2-mil traverse and the necessary amount of search

ure lJpplied to the gun after each burst. The 2-mil traverse is1I1Waysmaintained, but the amount of search to accompany

elleh traverse is varied to suit the target.

(3) The instructor then llas a man who has been previously

instructed in the exercise take his place at the gun to demon-

~trnt<!the exercise as follows:

(a) The instructor designates the two aIming points which

lire to be used to represent the oblique target, such as pastel'si~OS. 4 and 2, and requires the gunner to announce the com-

bination of searehing and traversing lle will employ.

(b) The gunner announces the combination he wllI use; in

this Cuse he will use ten 2-mil traverses to the right, each ac-




companied by a search of 1 mil up, and each followed by 8

simulated burst of fire.

(c) The instructor th~n announces the range and aiming

llOints. Example: Range 900, paster No.4 to paster No. 2.WheI1

the gun is properly laid, he commands: COMMENCE FIRING.

(d) The gunner repeats the command, sets the sight, layS

on the designated aiming paster and announces, "Up." At

the commanll, Commence firing, he simulates the firing of B

burst. lIe then traverses 2 mils in the required direction, ap'

plies the required :search, and simulates the firing of anothe1'

burst. lIe continues this operation until he has made tell

2-mil traverses, each accompanied by the required search.

During the exercise he watches the target and does not

at the gun or through the sights.

(e) At . the completion of the exercise the gunner

through the sights to see if the target has been accuratel~

followed; this is indicated When the line of aim is within

mils of paster No.2 in direction, and 1mil in eh~vation.Instructor Checks the.aim and points out any errors that eremade.,

(4) Each squad then performs the combined searching an

traversing exercise, practidng traversing to the right and

to the right and down, to the left and up, anli to the left and

down until all are proficient in the exercise. .

d. Dutil's 01 the cOtlch.-During each manipulation exercise1the coarh watches each soldier to observe the following points j:

(1) That the sight setting and laying are correct.

(2) That the proper position and hold are maintained. .

(3) That the soldier's estimate of the combination of search-ing and tra v('rsing is correct.

(4) That a uniform 2-mil search (where required) is used.

(5) That the tap, if the 1\11917 tripod be used, is uniform.(6) That in combined searching and traversing, the required

search Is correctly applied in connection with and after each

2-mll traverse.

(7) That the correct 2-mil traverse is obtained (when using

the :\11917 tripod) by adjusting the traversing clamp and not

by changing the force of the tnp. j

(8) That each soldier resumes the proper hold on the gunafter eaeh manipUlation and simUlates the firing of a burst

before manipUlating the gun ugain.

loolt

1001

:Th~

w.

up,

~

.




(9) That each soldier keeps his eyes on the target while

llunillUlating the gun and simulating firing.

(10) That, after la~'ing tile gUll, the soldier does not look

through the sights or at the gun until the exercise is completed.

(11) That the proper number of manipulations are taken as

reqUired. by the distance between the two aiming points being

Ul'!ed.

(12) At the completion of an exercise he checks the aim to

I'lPe if the proper point was reached in the exercise and points

(Jut any errors that were made.

74. Examination.-a. J~ach man who is required to fire dur-

Ing the marksmanship season IilUst be examined and rated as

Il1'Oficientin all of the preparatory training before he is al-

,1owe<lto fire a shot. The platoon leader will examine anu

rate each soldier when each phase of preparatory training is

('(lIUpleteu. l\:1pnwho are unsatisfactory will be given addi-

tlollal instruction until able to pass.




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b. The purpose of the examination is to enable the com-

llany commander to determine the state of instruction of each

Holdier at any time, and from this information to conduct the

COmpanytraining with economy of time.

SECTION III

COUHSE '1'0 BE InHED

'75. General.-a. Range practice eonsists of firing on the

1,OOO-inchange. The purpose of range practice is to provide

It means for developing proficiency in the four fundamentals

of machine-gun marksmanship as prescribed in paragraph 60.b. Each exercise in instruction amI preliminary practice will

he preceded by an explanation of the nature and purpose of

the exercise amI the proper method of carr~'ing. it out. If

time and ammunition are available, each exercise should be

flpmonstrated by an experienced gunner.

c. '.rIle purpose of the 1,000-inch range is to have a short,

known-distance range where the solflier can be given training\\lith service nmmunition ugainst targets of such a nature that

Ills errors may be reallily detected amI pointed out to him.

'l'he range must be short so that the strike of the bullets can be

l~asily sepn and the targets inspected frequently and without

flelay. The distance must be known, so that with a given

/timing point tIle exact center of impaet can be predetermined

for any sight setting and the re~mlts definitely checked. Undertllese conditions the soldier is given instruction in the basic

('lasses and vrineiples of fire and in the manivulation of the

gun in actual firing. One inch subtends an angle of 1 mil

lit 1,000 inches and simplifies these requirements.

d. '1'he course is divided into fl1ree parts-in:-;truction l)raC-

tice, preliminary practiee, and record practice.

(1) In:-;truetion practice teaches the first three fundamentalsflf marksmanship as I)l'escribed in varagravh GO. There are

)\0 time limits to tbe firing exerd:-;es in this practice.

(2) l'reliminary p1'lletiee l1evP]0I)S :-;lleed in the apllHcation

.,f the fundamentals of machine-gun marksmanship and is,

therefore, COlHluC'tel1nder a time limit.

(:3) Hceol'tl practice gives tIle soldier an object lesson in the

)lrogTesS Ill' Illls made and furnishes a means of classif~'inghim ae(,ol'lling to the profieiency IH' IHls nttained.

D8D:i3°-32--5



58BASIC :FIELD :MANUAL

76. The marksmanship course.-a. In8truction practice .....

InstructIon practice consists of the firing outlined in 'ruble 1,

suhjeet to the pl'ovisions ()f d below:

TABI.E I

Range I Time ShotsType of fire

,000 in •. Xo limit.Do ..•. .do. .•

Do .• _._ •• do._ •••.Do .••.. .• do ..•..Do ..•. •• <tn_ .•.•Do .••••. _.do ••••

3035

l'\O

120

"0

300

l\TG-Al\IO-AMO-BMO-CMG-D

MO-E

Fixed (3 exercises).Adjustment (l exercise).Sl'archinR (2 exercises).']'raversinK (3 exercises).Obl1<lue traverse (2 exercises) ..:Fixc( , searching, and traversmgcises).

(2 exer'

-b. Preliminary rJt'actice.-Preliminary practlec consists of the

tiring outlined in Table II, subject to the provisions 'of d beloW:

TARtE II

I,OOOln._. 3 minutes_ •• 150 MG-E Fixed; searching and traversing.

Hange Time Shots Target Type of fire

-c. Record rH-acfice.-H('cord practice will consist of twice

firIng the courSe shown above for Jlrelhninury practice.

d. Jlodi/icatioIl8.-Instructlon anti pl'ellminary r1ractlce will

consIst of the h'pes of fire prescribed in 'rables I unll II,omitting f'uch numher of shots, or such portions of certain

pl"Uctlce~, of Table I, ns may be necessary in order to keepwithin uIlllllunitIo'n allowances.

I

1

S~:CTlON IV

COXDCCT OP ItANOm PHACTICm

77. Officer in charge of range practice.-a. The officer ill

charge of range practiee is detailed hy the regimental or unit

<'ommanl1er for the purpose of coordinating the firing and

arrang.ing and sUIWrvising the uetails with reference to the

assIgnment of firing points. lIe is resIlonsihle for the rigid

application of safety pl"('cautlons by all units firIng. lIe wIIl

make time]~' requests to tlte range oflleer for repairs,. sUIlplies"

and alteration of Installations.

'

~ _

__ _ -

_ _ __ _

__

_



BASIC FIEI~D 1\IA:XUAL 59

b. During record practice he will be assisted by officers de-

tailed by tlle regimental or unit commander for duties on the

firing line as prescribell in paragraph 114.

c. During record practice lie will render decisions upon inter-IJretation of the rules governing re('ord practice which may he

l'~ferred to lIim.78. Range officer.-Successful operation of a machine-gun

rUllge requires the appointment of a range oUlcer well in ad-

vunce of runge pructiee. 'I'he chief duties of the range officer

ul'e as follows:

a. To make timdy estimates for material and labor in orderto 111aeetile range in proper eondition for tiring.

1).To supervise Hnll direct )'('pairs to im.;tallation~.

(~.To regulate the distribution of ranges and targets.

d. To maintain a storeroom where the materials requin'u

rHay be seeul'ed.C. 'Vhen safety delllands, to instruct and supervise range

J.:Uards.79. Company commander.-The machine-gun company <.'0111-

111111111('1' eondue1s the firing of his unit and is re:-:ponsible for

tll(~ ('ffieiency of its training.80. Safety precautions.-a. Firing will not lwgin on any

range until the offiN'r in eharge of range praeti('e ha~ u~.;('er-

tlli1led that the range is ell'ar and has given his authority.

11. No firing will lw done exc('pt under the direct supervisionof an offie('l'.c. No gun will he loaded or half loaded until a command to

(In so lias he<~ngiv('n.d. No gun will he lliSlllounted ufter firing until un officer

J IUi'l il1~11e\'t('dt to ~('e that it is unloaded.

c. No Jl('r~on will he allowed in front of the guns for any

)lurpose unt 11 dirp\'tn] by un oilie('r who has ordered tbat all~llllS III' dpared IIml has us('prtaiIj('d that tile order hus been

l'OIll11letelycurried out.,. ] hl1lger flags will 1)1'disl)la~'('d at prominent positions on

the run!?:eduring all firing.

fT. Suell range guards 11:'\ may he n(,fl<lt'llwill he po:-:tetl.

81. Uniform and equipment ...:-The uniform and equipment

to h(' worn during range pru('tiee will be prescribed by theJ't'gimental or unit communder.



GO BASIC :1"IELD MANUAL

82. Use of T base and sandbags.-Tl.le tripo<ls will be

mounted on a woo<len T base; sandbags will then be place

on each l<,g to steady and hold the gun to minimize vibratioIl.

Concrete T bases will not be used.83. Targeting the gun.-a. Before any barrel is used ill

marksmau!'hip firing, it will be targeted with the gun in whid]

it is to he used. The targeting vrocess is for the purpose 0

determining, an<l correcting for, the mechanical error of the

gun and barrel. The zero of a particular gUll and barrel i

the sight setting which will cause the center of impact of sho

groups mude by it to coinci<le with the exact aiming poinused. "'ith the nOl1nal gun this sight setting is 441 yards fO

1,000 i~ehes. By reason of llI11nufaefuring iml1erfeetions mo!'

guns have a zero other than 441 yar<ls. ..

b. (l) Firl~ a burst of 10 roun<ls 011 a target 1,000 incheSfrom the plntle of the gun.

(2) Determine by inspection the center of impact of theburst.

(3) Manipulate the sight (without moving the gun) in

elevation and direction until the line of sighting is on thecenter of impact.i

(4) Lower the sight leaf; loosen the screws holding the

sight-adjusting plate, and place the tips of the blades exactly

on the 441 graduation; make sure that both blades are se

in prolongation of this graduation (it may be necessary to run

the urift slide up to a range having lines on both branches ofthe sight to accomplish this) ; tighten the screws.

(5) Luy the gQn on an aiming paster and fire a confirming

burst; the (-enter of impact should be exactly at the point oaim.

(6) !\ote and record the (leflection zero.

c. The same gun will usuall~' have a different zero for eueh

barrl'l used. Once a gun anu barrel have been tar~'"eted, it

wIll not orulnnrily be nec('ssary to repeat the operation uuring

the life of the barrel. However, the packing must b~ done

properly, and the head-space adJustment correctly maintained,

In order that th~ Zl'ro may not be changed. 11'01' example, i

has been found possible to vary the position of the group on u

target as much as 4 mils by Wide changes in head-space adjust-

ment alone. Minor repaIrs tQ the gun will not uffeet the zero,

-

firml

both



I BASIC FlEW MANUAL 61

IIJUtmajor repairs, such as replacing the barrel extension or

the sight or cover, will necessitate retargeting the gun.

(1.When a gun appears to shoot inac'Curately it should be

l'l'tal'geted.

84. Use of fire orders.-All firing ,vill be initiated by defi-

II/te fire orders; the normal procedure is for the platoon leader

to ~ive the fire orders to his unit. '111egunner will be required

to rl'peat all fire orders. An example of a t~'pical fire order

Iiias follows: SPACE 40, HALF LOAD, RANGE 800, LEFT PASTER,

TRAVERSE, COMMENCE FIRING.

85. Personnel at the firing point.-During instruction and

l'I'l~lilllinaI'Ypractice thegunller, the assistant gunner, and the

('!llIch are allowed at the gun. The noncommissioned officer in

('!large of the gun, if he is not the coach, may be at the gun

\\'hen his presence is IH'eded.

86. Duties and use of coach.-A coach will be at each gun

\lUring instruction and l)l"pliIllinar~' practice. The success of

the instruction will depend to a great extent on the thorough-

Itl'",Sand exactness with which the coach performs his duties.

'J'heduties of the coach are us follows:

ft. To require the gunner to explain the practice he is about

to Perform.

b. To require the gunner to adjust the traversing clamp

. to his tap and to .inspect the gun.

c. To check the sight-setting and la~'lng, requiring them

to be correct.

d. To require the gunner to reset the sights and r~ay the

~Unwhen shifting from one group of targE:'ts to another in the

Nllrneexercise.

c. To observe the gunner's position, holding and manipu-

11ltlon during firing; if necessary, he may stop the firing to

eorrect errors.

t. To observe the target from time to time between bursts

to see that the gunner is controlling the fire.

U. To require the gunner to fire bursts as required for each

target. (A burst is n series of shots fired by one pressure on

the trigger mechanism.)

h. To require the gunner to observe the target while firing,

Ilnll to adjust the fire based upon this observation without

II'lIking through the sights.



'

62 BASIC HELD :MANUAL

i. To point out errors and explain their effect upon theexercise.

j. To keep eonstant watch of the adjustment and conditioJlof the gun.

87. Blackening the sights.-Both sights of the machine gUll

should be blackened to overcome the glare whenever the sigMS

are used for either range practice or preliminary instructioJl.

This is done by holding each sight for a few seconds in the

point of a small flame which is one of such a nature that t1

smooth, uniform coating of lampblack will be deposited 011

the metal. Among the most commonly used flames are 11

candle, a piec(~of camphor, shoe paste, a rag saturated with oil,or n carbide lamp.

88. Time Umi ts.-a. Before flring any exercise the gunner

will b(~allowed a reasonable time to examine and prepare biSgun and ('quipment. ,

b. In all firing with a time limit the gun will be half loaded,

l)rio1' to the command or signal to commence firing, the sightwill be rai~ed awl set correctly for the target to be ()ngaged, but

the gun will not be laid on the target. The cOlllpletion of the

loading and the laying will be effected after the command 01'

signal Commence firing.

'c. A warning signal may be g;ven not more than five second:;

before the eXPirati.on of the time lhll.it. ]'iring, will ceasethe command or signal Cease firing,

89. Laying the gun.-After the gunner has examined and

prepared the ('qulpment forfll'ing any exercise in preliminarY

llrnctice, the gun, with the 8ights cOl'l'ectly 8et for the particular

exercise to b,e 11red,will be l..'lid80 t.hat it, wi,ll.be a .ll.lill,imulllOf.

tj (hur'not more 'than 10) mils off in direction, and the same

aIllount In elevation, from the ainiing point 011 which it must

he laill for the initial burst. The gun having ill'en so laId off,

no person 'will make unr 'change In either its elevution 01'

dircctloil until the conllllund Commence firing is given. ThiS

llroc('uure will he followed' in eaeh ('xercise with each individ.

ual gUllJwr. DurIng IH'('liminary Ill'actice the couch will be (11.

rected to lay the gun initially as described nbove. The sightleaf will he rah;('d during nIl firing.

90. Stoppages.-l>Ul'ing llreliminury practice when a stop.

page occurs, the gunner will reduce the stoppage nnd' continue

the firing if nny time remains. The lloncommissioneu officer

at.



BASIC FIELD l\lAXUAL 63

hi charge of the gun will note the time r£'quired for the re-

(lUetion of the stoppage and will report the nature of the

NtollPugeto his platoon or company commander.

91. Targets used on the 1,OOO-inch range.-Machine-gun

tllI'gets will conform exactly to the specifications set forth in

tlte lllustrations of these targets. Alterations or additions of

ll.lly kind are prollibited .... (Figs. 24 to 28.) The targets will

Ill!Illade so that the outer bounda ry lines of the scoring groups

Will be distinctly visible from the firing point. A line width

or approximately three-sixteenths of an inch will be used.

1.he dimensions of the groups will be nH'asun~d from the outer

I

dI

d[jIcpQJ

..

Iq. ,

dchi

OJdJj

RANGES 700,900, 1100,1200, AND 1400 YARDS

FIGURE 24.-Machine-gun target A

"(]~es of the j'16-ineh line. The lines used to subdivide a scor-

Itng grou.p Into separate ~;{'oringspaees will be so made as not

to he visible from the firing point. The!"e latter lines will not

('Xeet.'tl one thirty-second of an inch in width. Before being

Ulolpdor record pl:actice, each machine-gun target E will be

ch,'eked by an officer to see that it conforms to the specifica-

tlolls prescribed herein.

92. Observation and adjustment of fire.-a. Tbe best results

III machine-gun firing will be obtained only when the fire can

h~ observed and adjustments made from observation. The

gUnner must watch the shot group as it is being formed to

~




--8---.- •

r6"Ir-9.7"

_!_.~ISqUare .• •

•

IJ

_Ran~e '000 to 5earch Up.1375to search down

FIGt.:RE2l:i.-Machlne-gun target n

I

t.p.21 I I I I I aL.9rr ......r---r-,

---r---TI-Ir---r---r--"'''-'J• I

j.. •••••••••••• -I6 .0 .....••••. i 20.4.

I I

-r-,. -,-, ....... I--r'--.I-r--' "T"""i-fiF. -0-.61" ! -.,.. _uJ--L-..L.-..I.--'---'---'---_r 1:

:12.8"I I •

...

1"--..--,.--,.--,...-,.-,--I -.iB~;3. !! [II : -T-

. i :4.7" .lc: I :

. .j_ ... _.~ ••.•

L 13••.••••••• ..••••• co. 13•..••.•.•. J

RANGES 800.IIOQ AND 1300 YARDSFIGURE2G.-l\[llchlne-gun target C

"--1

r :

' ~ _

~ ~~




e('ure the maximum effect of observation. In making the ad-

~~trnent the location of the center of impact is aseertained;

e gUn is then manipulated to place the center of impact

. --~a.lI II

'1'-- --;.

,~.r.~l. ~~~---4.l0 4.7" 7" L I ;-, ...

13" 1. 1311-U-llIO

RANGE:S 800 AND 1100 Y,l,RDS

FIGURE 27,-Macbine-gun target D

11the center of the scoring space. Precision in securing the

IC('uratedelivery of the initial burst will reduce the need forIdJul5tmentto a minimum. Observation of fire on the 1,000-

-~ t..,, .

I

!/0 .... ,38•

.-",..

IlLs-, ...•0 II

• I

; I

il !••.•• *- .•••

RANGES 1300.800.1000.& 900 YARDSFIGURE 28.-Machine-gun target E

Ch range is relatively simple because the entire shot group

11be sepn with respect to the sC(lring spaees. Adjustment

tile gun and tripod to secure a compact shot group, locating

•

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_ ~

j

_ -



GG BASIC FIELD l\lANUAL

the line of "fire so that the sun is back of the target, and P

ing. the targets so that the sky line is beneath the scot"

spaces are all important factors in improving the possibil

of observation. One inch on the target at 1,000 incbeSequal to 1 mil; bence for a shot group having a center of

pact 4 im'hes to the right of the target the gunner must aP

two 2-mil taps, moving the muzzle to the left; for a shot g

2 inches low the gunner must elevate the muzzle 2 mils (

clicks) by manipulating the elevating handwheel. The sol

will be given a series of exercises in which he must state

amount and direction of the correction for shot grouPSvarious locations with respect to the target. .

b. Instruction in the classes of fire (eh. 3, Sec. IV) and

nature of the cone of fire (par. 132) will be given in connect

with this practice.

93. Instruction practice, grouping, machine-gun tat

A.-a. Purpo.'te.-The purpose of the grouping practice

machine-gun target A is to teach proper grouping and therect method of delivering the initial burst of fire. (Fig.

b. PractiCe.-This practice is fired as three separate e,

cises. In each exercise the gunner lays on the designated

ing paster and fires 10 rounds as one burst. Upon comPleuo

th~ burst he checks the aim to see if the firing has disturbe

Any three of the four lower scoring spaces of a vertical se

are used. Sight settings to be utilized to strike these four S

ing spaces are 700, 900, 1,100, and 1,~00 yards. The

maintains the proper vosition, keeving his eyes on the tar

during the firing of the burst. Careful attention will be

to his hold. The resulting shot group, to be satisfactory,

be cOlltainro within an oval 2% inches high and 2 inches

(This should be true of any shot group, in any exercise on

1,OOO-inchrange.) Errors in location of shot groups are

to a poorly-mounted or adjusted gun, to incorrect sight set

or la~-ing, or an incorrect hold. .

94. Instruction practice, adjustment, machine-gun ta

A.--a. Purpoxc.-The purpose of the adjustnwnt practice'

machine-gun target A is to tpuch ohservation of fire and

adju:-itment of fire from observation.

b. Practicc.-The practice Is fired as one exercise. The

tlscoring space of a vertical series is used. The correct •

setting for this scoring space Is 1,400. The gunner is

gu

.

gl

sh

'

gi"



BASIC FIELD l\1ANUAL 67

ght !!letting which is in error by about 100 yards in elevation

~(l4 mils in deflection, such as Range 1,300, sight right 4 and

, l'equired to lay accurately on the appropriate aiming point.

Ioiel'iesof bursts of from six to eight rounds per burst, not

l eXceed 35 rounds in all, are fired. Firing will cease as soon

It burst is observed to strike the center of the scoring space .

.!! each burst is fired, the gunner observes the strike, and

~en.without altering or .looking through the sights, adjusts

e gun by means of the traversing and elevating mechanism to

i'lng the center of impact of the next burst on the desired

~lnt. If the second burst does not strike in the correct posi-

~n, adjustments are again made, and a third burst is fired.

then the fire has been successfully adjusted, the practice is

I~lllled. The gunner, without moving the gun, adjusts "the

ght until the line of sight is ag-ain accurately on the aiming

~11lt. He notes the elevlltion and deflection settings and an-

~OUn('eshem to the coach. If the exercise is correctly per-

~i'lUedand if the gun has been properly targeted, the eleva-

;lU should be found to be 1,400 and the deflection the zero

: the gun.95, Instruction practice, searching, machine-gun target

I}-u.•Purpose.-The purpose of the searching practice on ma-

.line-gun target n is to teach the proper distributioll of fire over

(le(~parget. (Fig. 25.)

b, I'raetioe.-The searching practice is tired in two exercises.

I the first the gunner lays on the designated aiming point with

!lIght setting of 1,000 yards, and fires 40 rounlls, endeavoring

111stribute the fire uniformly over the 2 by 16 inch scoring

,roup while searching up. The second exercise is fired in a

rllllJar manner while searching down, using a sight setting

. 1,375 yards in la~'ing the gun. A different aiming point

ill he taken for the second exercise. The firing is done in

1~Cel'lsivebursts of about five rounds each, the gun being

eVIlt<~dr depressed between bursts to obtain proper distribu-

on, The gunner watches the target anll makes the adjust-

etlts necessary to maintain proper direction and to obtain

I1lformdistribution. Inasmuch as a very important phase of

Ie rlractlce Is the proper distribution of ammunition over the

)'bOle scoring space in one application of fire, the gunner will

! InHe firing when he reaches the end of the scoring spaces,

th'JUgh be mllY not have exhausted the ammunition allowance.

~

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G8 BASIC FIELD MANUAL

96. Instruction practice, traversing, machine-gun targ'

C.-a. Purpoxe.-The purpose of the traversing' practice

machine-gun target C is to teach the proper distribution of :6

(lver a wide target. (Fig. 2G.)

b. Practicc.-This pmctiee is' fire<1 in three exercises.

the first and third the gunner la~'s on the left aiming poi

of the group with sight settings of 800 an<11,800 ~1ar<1s,eSP

tively, and fires 40 roun<1sin each, endeavoring to distribute tfire uniformly over the 2 by 16 inch gl'OUp while traverlll

from left to right. The second exercise is fired in a simil

manner, traversing from right to left; the right-hand aimi

point Is use<1with a sight setting of 1,100 yards. The firi

is <1one in successive bursts of about five rounds per bur

the gun being change<1 in direction between bursts to obt

proper distribution. The gunner watches the target and ma~

adjustments necessary to maintain proper elevation and obttl

uniform <1lstribution. The gunner will cease firing when

reaches the end of the scoring spaces, although he may not h~

exhausted the ammunition allowance. Care must be taken

insure that' the gunner adjusts the traversing clamp to

tap before he fires the traversing exercises.

97. Instruction practice, combined searching and trave

ing, machine-gun target D~-a. l'urpo.'lc.-The purpose of

combined searching antI traversing exercise is to teach

proper distribution of fire over a target requiring a CO

bination of searching and traversing. (Fig. 27.)

b. Pl'acticc.-This practice is fired in two exercises. In

first the gunner .lays on the left aiming paster with the sig!

set at 800 yards for the lower scoring spaces, or 1,100 yat

for the upper, and fires 40 rounds, endeavoring to distribt

the fire uniformly over the 2 by 16 inch scoring group

traversing to the right and searching up. The right aim

paster will be used for the :second exercise in which the guni

traverses to the left and searches up in a similar

All lessons learned in the searching and traversing exercli

apply with equal force to thi8 exercise.

98. Instruction practice, combination, machine-gun taii

E .-a. l'ur[w.'le.-The purpose of the instruction practice

machine-gun target E is to deVelop further skill in the appll

tion of the fundaml?ntals of machine-gun fire to the

types of targets. (Fig. 28.)

wl

man

sev



BASIC FIF.LD MANUAL 69

~.Practice.-The gunner takes his place at the gun witl:..

rOunds in the belt. The gun is half loaded and the sight

: at 1,300 and raised. The coach lays the gun so that it is

tt1ininmmof 5 (but not more than 10) mils off in direction

d the same amount in elevation from the first aiming paster

be Used. The gunner is required to know the proper sight

:t1ng for each group on the target. These sight settings

1,300 for the fixed-fir~ target, 800 for the traversing tar-

, 1,000 for the searching target, and 900 for the combined

\'er8ing and searching target. The groups will be engaged

the gunner in the order named above. At the command

Elignalto commence firing' the gunner completes the loading,

tile gun on the left aiming paster, and then attempts to

[trIbute the fire uniformly over the four scoring groups

i the target. 'Vhen shifting from one group to another he

!

l'elIUiredo reset the sight and lay the gun on the proper

lng point.

o. EJ1Je()ia~reparation.-Before firing, if time is available,

I gUnner should be required to go over the target, simulating

Qttg at the various scoring groups in the prescribed manner.

9. Preliminary practice, machine-gun target E.-Prelimi-

l)r Practice on the machine-gun target E is fired in the

llte Inanner as the instruction practice on the same target,

eellt that there is a. time limit of three minutes, and the

ttnerceases firing when the command or signal is given. This

get Is scored as prescribed in paragraph 112a.

SECTION V

nULES GOVERNING RECORD PRACTICE

00. General.-a. In record practice the gunner takes his

eealone at a gun to fire an exercise with a prescribed amount

I IlnlInunition in a given time. During this practice he mustthe sights, lay the gun, and fire without any aid, coaching,

ll~fSlstancewhatever. The regulations of this section pre-

Ihe the method by which this principle will be carried out,

it rUlings on the more common points •. "rile gun'ner should have a thorough course of preparatory

hllng, a gun in excellent mechanical. condition, and firmly

Ullted, ammunition whleh is the best available, and time tolJecthis gun and ammunition before firing record.

~

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70 BASIC FIELD MANUAl.

c. Tile general conduct of the firing will be under the di

charge of the officer commanding the organization.

101. Officer in charge of range practice.-The officer

charge of range practice is charged with the resvonsibility

supervising and coordinating record practice in strict

formitJY

with these regulations. lIe will rule in accordance \1'

the regulations on aU points that may arise during reepractice.

102. Order of instruction and record practice.-a.

person will complete instruction and preliminary practice

fore procpec}ingwith record practice.

b. When record practice is once begun it will be cat'to completion before any other practice is permitted.

c. As a rUle record practice will not be fired by any soilon the same day that he fires any vart of instruction or I

1iminar~' practice. However, when the time allotted to rll

praetice Is "ery limited, the otlicer in ('harge of range prac

may authorize reeord firing Oil the same day. Instruction

preliminaQ' practice will not be conducted simultaneotwith record practice excevt on ranges where firing takes pIon a different part of the range.

103. Retargeting.-The provisions of paragraph l02b all

will not be construed to prohibit the retargeting of a gll~

at nny time this becomes necessary.

104. Personnel at the guns.-The use of a No.2, a co

or any other person at or near the gUll while a soldier is firor preparing to fire recor(l practice, is prohibited.

105. Position of sight leaf.-The sight leaf will beraised dming aU firing.

106. Time for inspection.-The gunner will be nllowe

reasonahle tlLle for the examination of gun, ammunition,equipment.

107. Gun and ammunition to be used.-a. The machineand tripod as Issued hy the Ordnance Department will be t

in all firing. Tile Use of additional clamps or applIanceS

any kind on the gun or tripod is i)rohibited. This provi

will not he construed to vrohibit the Use of shims or wasl

for the purpose of keeping the gun or tripod in proper aM

ment. The sights may be blackened. The panoramic S

willnot be used.

~



BASIC l"IELD MANUAL 71I~b. 'rhe ammunition used w1l1be the service cartridge a8 i88ue<l

1J the Ordnance Department. It will be carefully examined

l a defective cartridges eliminated. The use of tracer ammuni-

lOUisl))'ohibite(l.

108. Sighting shots.-Sighting or ranging-in shots are

O!libited.

11?9. Accidental discharges.-:-After a man has ta~en ~iS

bllte at the gun for any exerCIse, all shots fired by hIm WIll

\lilt IlS a part of that exercise. The total amount of am-

llnition used in any exercise, including shots fired acciden-

rlJ y, '\ViII 110texceed the amount authorized for that exercise.

110. Use of prescribed aiming point.-The prescribed aim-

POint will be used in laying the gun. In all exercises

fl essitatlng a shift from one aiming point to another the sight

III be re.,se.twith the proper sight setting and the gun relaid

tl\aking the shift.

~111. Firing after command or signal to cease :firing.-In

~lDractlces which are scored, one point will be <leducted from

e SCore of the firer for each shot fired by him after the

!llillarHIor signal to cease firing has been given. In any

eb.case the minimum p('nalty will be five points regardless

the number of shots so fired. The assistants to the officer

Charge of range practice will exact this penalty.

112. Scoring rules.-a. The machine-gun target E is scored

fOllows: Two points are scored for each 2-inch scoring space

t; one point is scored for each hit in a scoring space, but

~t tnore than six hits are counted in anyone 2-inch scoring

liCe. Hits touching the boundary line of a group are counted.

\hit touching the line between two 2-inch scoring spaces is

Illnted in only one space, but the space selected is that which

I

"ea tile greater score to the gunner. The total possible score

200 volnts.

Ib,.A. f!('ore card will be kept for each person firing as a

~ord of the seores made in each part of the preliminary prac-

IIIand record practice find of the total score made in each of

~ioleructices. The qualificfition attainpd and the date it was

(leWill also be recor<1ed. Entries will be made in ink or in-

lble }l{.neil. No erasures will be ma(]e on score cards.

Iterations may be made only by the organization C0111mander

an oiJieer acting as seorer, and eaen alteration will be

thentkated by the signature of the officer who made it.

~

~

~ ~

~

~

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c. In record practice all tal'gpts will be scored by an ofJi

who will enter the score on the score card and authentltthe entry.

d. If a man fires on another man's target in any exerc

he will receive u score for such hits as are shown 011 his (I

targl't, but he will not be allowed to fire the exercise ag:

The man on Whose target he fired in error will be requirefire the eX(>l'ciSI~gain.

113. Stoppages.-(J. When a stoppage occurs which

gUIHwr ('an not reduce hy draWing the bolt hundle to the

and releasing it, he will raise his haTH}and call, "Time."

time remaining for tile exercise will he Jwted mrefullY

tile assistant to the officer in charge of range vractice. ,~ ~

the 8topvage has b('en corrected, the gunner will he a1l0 I

the time r('mnining for the completion of the exerC'is(~as Il

by the otncer at the instant the stoppage occurred, unlesS I

cause of tile stoppage was manifestly the fault of the gUll

In which case the score must stand. In no case will the e

else he refired. Should a breakage otcur the gun will be

targ(.ted or replace(} amI the score com[lleted. ~j

b. If, in the course of reducing any stoppages not due t(1

fault of the gunner, any unfired rounds are l:'jected froIll II

gun, the gunner will be allowed a(lllitional time to

his score aft('r tile expiration of the time limit, Oil the b

of 1.2 seeonds for each round.

c. The otlker in charge of range practice will render I'

deeisions on stoPvages.

d. Before the cOlJJmand Commence firing is given to COIIl

the exercise the gunner will be 11Pl'mitted to relay upoo

target at Which he was firing at the time tile stopl)uge occut'(

114. Duties of the assistants to the officer in charg'

range practice.-A number of officers sufficient tosupe

record praetiee in 8ft'let aeeordanee with' the Vrovisions of

"ecUon will be d~.tail('d to assist the officer in charge of r,

praeUce. 01liecrs for this duty will be detailed from eomp I

not firing. A maximum of two guns ean he supervised by

oflieer. lIe will perform tile follOWing duties in person:

u. Count the ammunition for eHeh' fin'r after lie takeAOl

pl:1ee at tile gun.

b. Chpek tile (limensions of the scoring spncps in accordwith para,g,.uph 91.

'

!

cOlnJ!

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o. Lay the gun off the aiming point not less than 5 nor more

an 10 mils in direction, by tapping, and not less than 5 nor

ore than 10 mils in elevation by manipulating the elevating

llldWheel,after the soldier has set the sight and laid the gun

I desired. Thereafter, the gunner will not alter the laying ofe gun until after the command or signal to commence firing is

'en. Care must be exercised, however, to have a part of the

Illingpaster visible to the gunner after the gUll is laid off.

fl. Hequire that the gunner pull the bolt handle once to the

flr after the command or signal Commence firing.

e. Be watchful for the occurrence of stoppages and note the

:ll.cttime consumed in reducing tbem. In cases wbere theInner does not complete the firing within the time limit

iCel'tainthe exact cause, and secure a ruling from the officer

Charge of range practice as to completing the exercise.

f. lIe will require that tbe prescribed aiming point is used

l<l Dot the scoring space; for example, the use of a sight

,tUng of 441 yards with a scoring space as an aiming point

~Decificallyprohibited.0. Make the <1eductioll for firing after the command Cease

illg• .

h. Count the total number of shot holes on a target and for

eh hole above 150 deduct three points from the total score

Qde.

t. Count and record the score as prescribed in paragrapb 112.

115. Disqualification.-Any <1eparture from the mandatory'ov!f;;ionsof this manual in firing record practice will dis-

talify the man affected both for pay and qualification purposes.

SECTION VI

JNSTHUCTION OF TAHGI~TS, RANGES, AND EQUIP.

MENT

116. Range construction.-a. The number of firing pointsIII Jepend upon the terrain available and the number of guns

ieh will probably be firing at the same time. For a company

, eight guns eight firing points are desirable. The interval

!tween guns should be approximately 5 yards.

b. On aecount of the small size of the 1,OOO-inchrange a

Cation for it can be found easily. For each target there i~

!quired a level, open space about 40 ~'al'ds in length (in the

980:m o-32--6



74 BASIC FIF..LDMANUAL

TRACKS-

TARGETS

CUJ CUJFIRING POINTS

direction of the line of fire) and about 5 yards in width.

can be located 1'0 that the fil'e is delivered into a steep bll

such as the side of a ravine or an artificial bullet stop,

thus eliminate the necessity

range guards. On this range

interval between guns may be

dm'ed to 3 yards when necesSll

On the 1,OOO-inchrange the

observation of strike is obtaill

when the light is f"om behind

target. Since firing is usually d

in the morning or early afternO

the best direction for the line

fire on the 1,OOO-inch range

slightly east of south.

c. On the 1,OOO-inchrangetarget frame may be carried 0

('ar which runs on a light tr

leading from the firing point to

position of the ta rget, a dista

of 1,000 inches (83 feet 4 inclle

measured from the pintle. r

car and track are furnished byFIOt;RE 2n.-Pllln of 1,000 inch Ordnance Department. Hope

muchine-gun range furnished so that the carria

may be drawn back and forth by a man standing at the

point. This facllitatfls target (.'hanges and observation of

snIts. The arrangement of the range and equIpment is shoWIl

.------1000 in --------...,

FIGURE 30.-1,OOO-lnch range

Figures Z> and 30. CarrIages and tmcks are not a necessity

may he dispensed with, tlte targets being supported by sta~

drh'en In the ground at the required distanee from the

point. In eitiler ('a", tile Btake. Bupportlng tile tnrget on

1

fir

.

fir



I


1I.1'1'1age or on the ground should be placed fit the ends of the

~'get frame. When placed back of the target they fire soon

ot Out and also interfere with observa tion.

117. Construction and use of T bases.-The following is a

hll1leor the construction and use of T bases:

!a. Make the T base to fit the particular tripod with which

Is to be used.

b. ~Iake the T base of 2 by 6 inches or heavier timber, if

.

~IlUable. Two pieces about 4 feet long are ne.eded for each

k bllRe• The juncture of the two pieces should be a flush,

Ilpe(} joint so that the T base will lie flat on the ground.

c. When the T base has been made, set the tripod on a level

or and carefully adjust it until it is at the proper height

111.1' the normal sitting position and the traversing dial is accu-

tely leveled. Next place the tripod on the T base and accu-

tely mark the location of the cleats of the legs and trail.'

\ltnovethe tripod find carefully cut out grooves of such size

/l.t the cleats will fit snugly in them. These grooves must all

I! or the same depth so as not to disturb the level of the

ll\,ersing dial. The T base should then be numbered to cor-

~llondto the tripod with which it is to be used.

d. In placing the T base at the firing point, carefully level

I!ground and dig a trench whleh will just receive the T base

a leave the top of the base at ground level. P:ace the T basethe trench, level it, and tamp the earth around it to seat it

tnly•

118. Use of the sandbag.-Half fill the bag. Set it on end

d fold the upper half of the bag so that it lies flat along

III filled portion. Place the bag firmly on the leg or trail of

e tripod so that the foMed part of the bag is next to the

({or trail and so that the bottom of the bag rests on the

oUnd. In placing the bag on the trail tamp it down so as

llluke a good seat for the gunner. Two or more bags on the

~sare neeessary to secure a stable mount.

119. Construction of 1,OOO-inch targets.-The following is

gUide for the construction of 1,000-inch targets when the

rllnlllleeDepartment is unable to supply them:

a. '1'he maldng of 1,000-1nch targets cnn be greatly facilitated

I the use of stencils. l'roeure a picee of tin or cardboard

Il~h is Inrge enough to ('ontain one complete group of the

1l~1'8 needed for the target being made. Draw accurately on

the spa('es and aiming points for the target in question, using

~




a straightedge and n sharp pencil. Carefull~1 cut out t

spaces and aiming points. Such a stencil can then be used

make n large number of targets if! a short time.

b. Place the stencil in the proper position on the 1,000-io

target with the boundary lines of the' scoring spaces in tll

proper relation to the edges of the target. With a sharp peIl

uraw in the spaces and aiming points on the target. Remo

the stencil Paste black target pasters on the aiming poill

as located. By use of a black crayon or other means wid

the outer bounuaries of the scoring spaces to three-sixteent

inch so as to make them Visible from the firing point. Drtl

these black lines just inside of the pencil lines showing t

outer boundaries of the spaces. Draw in the. necessary !ill

to subdiylde the group into the required number of 2-inch sc

ing spaces. Use a sharp pencil for making these lines and

not thicken them to make them visible from the firing

Care is required to make the dimensions conform exactlythose prescrihed in Figure 28.

c. Where facilities are available, it will be much betterhave these targets printed.

SECTION VII

ADVICE TO INSTRUCTORS

120. Provisions not mandatory.-This section is Includ

as a guide for officers in charge of machine-gun marksmansllflinstruction and will not be considered as haVing the force-

regulations unless so SP~~ifically provided elsewhere.

121. Arrangement of demonstrations.-a. Demonstratlo~

which are sklUfclly conceived and executed are a great

in increasing interest in the work, which in turn has a dir~

bearing upon the efficiency of instruction. Successful

strations are necessarily short and give the soldier a

picture of the duties he is to perform.l

b. The men who are to demonstrate an exercise should

intelligent, neat, and soldierly in appearance. They should.

carefully rehearsed in the exact duties each will perform

ing the demonstration, and Where time permits they

practice until it is certain that the work will proc('Cd smootbt

and 11lustrate clearly and simply the exercise which the UIl1

Is tb carry out after the demonstration. ,Co Interest is added to the demonstration by including

mon errors, the officer or noncommissioned officer conductill

poi

.

fact

demo

Clean-e

.

dt

shoU

co

'




the exercise indicating the error, its effect, and the proper

action.122. Organization of work.-a. Thought must be given to

the efficient use of time and equipment during all marks-

lnanship training. For all actual work at each gun a maxi-

lnUm of four men can be advantageously instructed, particu-

1urly during the preparatory exercises. On the range during-

actual fii"ing much can be learned by watching others fire.

'rhe requirements for making targets, filling belts, and fatigue

<It'tails will absorb surplus men. Physical facilities, such as

lnachine-gun equipment and range facilities, should be used to

their maximum capacity, subject only to the necessity for

adequate supervision.b. A demonstration platform should be provided in a central

ll(jsitiOll so that the men under instruction may be assembled

qUickly. A roped area is entirely satisfactory for groups of

100 men or less with the limiting factor that all must be able

to see and hear everything that is said or done.

c. A careful allotment of time should be made for each step

in the training. However, the instructor must watch the

llrogress carefully to see that the men master the instruction

thoroughly, and still are not kept at one exercise to the point

of boredom. Frequent rotation of duties within each group,

\\'1th each man performing each phase of an exercise several

tImes is preferable to keeping each man in one position for a

long time.123. Range organization.-a. Systematic organization of

\\'ork and layout of equipment is necessary for efficient instruc-

tion. Range practice should proceed in an orderly manner,

and the whole organization plan should be developed with

this end in view. Thought and study by the officers conducting

this instruction will go far in securing this desirable end.

b. Belts should be loaded and targets constructed so that an

adequate reserve is on hand at all times .. Time may be saved

by plainly marking the loop ',,"hich holds the last round of

the 150 for record practice. The requirements for all spare

(Iurts and equipment must be foreseen so that firing need not

be stopped because of failure to anticipate needs.o. Tbe ground around all gun positions should be kept clean,

l!lnootl~,and well paclted. A sack or cloth should be spread

Under each gun to catch empty shells; this will facilitate their

Collection and keep them from being filled with dirt. A rack




or box should be provided for keeping the belt from getting

in the dirt as it comes through the gun during firing.

d. Cleaning raeks or tables should be provided for each gun

or group of guns WhE're guns and equipment can be cleaned

or repaired without danger of falling in the dirt.

e. An adequate supply of clean water should be provided forrefllling water jackets. .

,. AU of the points to be observed before, during, and after

firing, as prescribed in paragraph 24, should receive careful

attention and have a definite place in the schedule of work.

u. The packing of the balTel should be frequently inspected

and rpplaced when necessary. The front packing should re-

ceive particular attention, for it exercises a great .influence on

the nature of the shot group made by the gun.

h. The prompt publication on the company bulletin boards

of the seores made in preliminary and record practice will be

of great value in stimulating interest and arousing a spiritof cOJllpetition.

i. Men who are not actually engaged at the guns during fir-

ing or detail<'d on other duties should observe the fire. Benches

should be provided in rear of the guns so that men may sit

in comfort rather than stand or sit on the ground or ammuni-tion and water boxes.

124. Adjustment of gun and tripod.-a. During range prac-

tice each gun and tripod should be properly adjusted, mounted

firmly on a substantial T base, and the tripod weighted down

with ~andbags in order that the gun will group closely. Since

the purpose 'of marksmanship is to master the four fundamentals

prescrib{'(l in paragraph GO, instruction is greatly simplified

by providing £>quipmentin perfect mechanical condition.

b. Looseness and play in the gun must be. reduced to a

minimum consistent with proper functioning. This is accom-

plished with proper packing and tightening the. muzzle gland.An incorrect h{'ud-spaee adjustment affects the size of the

shot group. ""orn or bent parts must be corrected or replaced.

Play iuthe sight or Cover affects the accuracy of aim. Shimi'l

should be inserted around the elevating pin or trunnion pin

if an~' loo~'ne8s is pre~{'nt. The brass slide in a cartridge

clip is excellent material for this purpose.

o. Several parts of the tripod reqUire attention. In a tripodwhich has been in use for an extended period the sides of

the cradle should be forced inward so that the trunnion block




is firmly held. The elevating mechanism must be withoutunnecessary play; this can be corrected by tightening the'

tumbler collar under the elevating handwheel, and by insert-

ing shims around the tumbler trunnions. The serrations on

the tripod legs must be sharp.

d. Once a gun has been properly tightened and adjusted it

8hould 110t be removed from the cradle. At the close of

firing the traversing clamp can be loosened, the gun and cradle

being lifted out together. This eliminates the necessity for

daily adjustment and saves time.

125. Inspection of ammunition.-Care should be taken to

See that the best ammunition available is reserved for record

Practice, and that all ammunition Is carefully inspected before

It is used so that obviously defective cartridges can be elim-

inated. If 'this is done, the firing will be more accurate, the

guns wlll function better, and there will be much less trouble

from stoPl)ages. For record practice, especially,. every round

8hould be examined. This can be accomplished by having each

lnan examine his own ammunition while awaiting his turn to

fire. The following points should be covered in inspecting the

ammunition:

a. That it is properly amI evenly loaded in the belt.b. That the bullets are all tight in the cases; loose bullets

tan be detected by attempting to twist them.

c. That the cartridge cases are clean and free from bulges,

dents, or spilt necks.

d. That the bullets are not shoved so far into the case ns to

make short rounds.e. That the rims are not too thick and are not battered.

126. Spare barreis.-An :HI~'qllat(~ supply o( sei;,;Ice:lIil(' ,in-I::'

l'eJs must he on hand for lIlarksm:inship fIrin,a-. The 8"ccuracy

life of barrel depends on the care and attention which it'

receives. In firing at aerial targets it is important that the.

Water jacket should be completely filled with water. Barrels

Which have been used for firing approximately 8,000 rounds

of ball ammunition which are badly eroded and pitted, or

Which have been used for firing a large quantity of tracer

ammunition should 110t be used. For marksmanship firing

. and for firing at aerial targets such as free balloons, where

the balloon release detail is in advance of the guns and not'

r.ompletely protected, the accuracy life of a barrel is placed"

""hO"~ fihould be, if available, one barrel'.---.-.l..;n 'course.

~




131. Value of direct laying.-The possibility of observing

the target and the effeet of fire, and the ~onHequeut siluplicity

of fire adjustment, give to direct laying a relatively greater

('fficiency than that possessed by indirect laying. Taking- iutoconsideration the number of casualties inflicted upon the enemy

within a unit of time with a given ammunition expenditure,

it may be laid down as a general rule that fire by direct la~'ing

is much more effective than by indir('ct la~'ing. The former

is the type most often employed in battle. It should alwa~'s

be used in prpference to indirect laying when a practicable

choice exists between the two. However, indirect laying shouldsupplen\('nt diret't laying whenever there is a possibility of the

failure of the latter method on account of smoke or darkness

masking the target.

SECTION II

COXE OF FIRE AND BEATEN ZONE

132. Cone of fire.-a. When a series of shots are fired in a

single burst the bullets do not all follow the same path, nor

do they all strike the same point on the ground. The vibra.

Uon of the gun and tripod, the variations in the ammunition,

and the changes occurring in atmospheric conditions, cause

each bullet to trace a trajectory differing slightly from that of

the others. The resultant group of trajectories is known as

the cone of fire. This cone may be cOlllIlared to the stream

of water frolll a hose. At ranges up to 700 ~'ards over level or

uniformly-sloping ground, the stream of bullets does not rise

above the height of a man standing. However, as the gun

is elevated to fire at the longer ranges, the cone is lifted con.

siderably above the ground. Thus at the longer ranges it is

possible for the gunner to deliver supporting fire over the

heads of friendly troops.

b. As the bullets travel farther from the gun the width of

the cone increases uniformly at the rate of about 2 yards for

every 1,000 ~'ards of range; meanwhile the height increases at

a much greater rate.

133. Beaten zone.-a. When the cone of fire strikes the

ground it forms a long elliptical pattern. This pattern is

!mown as t11e beaten zone. The lengths shown in ]'igure 31

are attained when the cone of fire falls on ground whose

surface Is parallel to the line of aim. The maximum length

Is obtained when the slope of the ground approximates the




angle of fall. On rising ground the width remains the same,

but the pattern is shortened until, on ground perpendicular

to the line of aim, the beaten zone becomes the same as the

\'ertical pattern (cone of fire). (Fig. 31.)

b. The center of the beaten zone is called the center of

impact. It has been found that most of the shots are uni-

FIGURE 3t.-Effect of ground slopes on beaten zone

formly grouped about the center of impact, and that the

number in a given area decreases gradually as the outer

limits of the beaten zone are approache{l. The grouping of"hots is shown in Figure 32. The shots are so scattered along

the outer edges of the beaten zone that the entire pattern is

not regarded as effective. Only that part of the beaten zone

j.--- E.ff.E.CTIV.E. Df.ATEN ZONE.' ----tlI (est. ZONE.) I

:~'.'.:::;\'.'i'Y~;rt(;:.i,:(~I CE.NTE.R OF IMPAC.T II. IIt . 10010ZONE

FIGURE 32.-Distribntioll of shots in beaten zone

2n which 85 per cent of the shots fall is considered effective

against milchine-gun targets; this area is known as the "85

Per cent" or "effective" beaten zone. It is obvious that the

maximum effectiveness can be obtained only when the center

of impact is placed on the target. The machine-gun sights are

graduated so that when the gun is laid on a point, with the

('orree! sight setting, the mean trajectory, or center of impact,

8hould'strike that point. The gunner is taught to do this in

lnarksma nship.c. FIgure 33 shows the approximate dimensions of the effec-

tive beaten zone on ground surfaces parallel to the line of aim

at the key ranges. All machine gunners must know these

'



84 BASIC FJELD MANUAL

l::fOO

dimensions as a basis for estimating the lengths of effectivebeaten zones on varied terrain.

d. Throughout this chapter whenever reference is made to

the beaten zone it will be llnderstooll to mean the effective

beaten zone, unless othenvise specifically indieated.

50~"".2000

FIGURE 33.-Table of approximate effective beat~n

Zones on gronnd parallel to the line of aim forM1906 ammunition (triO-grain bUllet)

SECTION III

RANGE DETEU:\IINATION AND WINDAGE

134. General.-Correct range determination is highly im-

llortant for efficient machine-gun fire, since it is often impossible

for the gunner to adjust his fire because of damp ground or

poor visibility. In such cases the cone of fire may miss the

target completely if there is an error in range no greater than

100 :rards. In direct la~'ing, ranges are usually determinedby estimation, by the use of range finders, or by fire foradjustment.

135. Classification of ranges.-a. Ranges are classified asfollows: .

(l) Close, under 700 yards.

(2) Mid, from 700 to 1,200 ~'ards.

(3) Long, from 1,200 to 2,000 ~'ards.(4) Distant, over 2,000 ~'ards.

~

~~




b. Ordinarily ranges vary. from 100 to 1,500 yards for direct

laYing. Practically, the extreme usable range is governed by

the means of determining the range, by the visibility, and by the

tactical purpose of the fire.136. Methods of range determination.-a. Ranges may be

<lPtermined by anyone of the following methods:

(1) Estimating distance by eye.

(2) Range-finding instruments.

(3) Fire for adjustment.

(4) Taking the range from a map.

(5) Obtaining it from other units.

(G) Measuring- the range directly on the ground.

b. In. using direct laying, the methods of range determina-

tion usually employed are estimation, range finders, and fire

for adjustment. Ranges determined either by estimation or

range finder should be ehecked by fire for adjustment whenever

llJ'ucticable. When observation of. fire is possible and surprise

{'fl'ectis not important, determination of the range by fire foradjustment will give the best results, because the gun itself,

Under favorable conditions, is the best range finder.

137. Training in range estimation.-The methods of train-

ing in range estimation prescribed in l)art One, Chapter G, will

he followed. All l)erSonnel of machine-gun organizations should

h(~ trained to estimate distance with a fair deb'Teeof accuracy.

Officers, noncommissioned officers, un(l Nos. 1 and 2 of the gunklJuads should receive additional instruction with a view to

l'(mching and maintaining a high degree of proficiency in this

kUbject. The average of a number of estimates by different men

Will usually be more accurate than a single estimate. Platoon

It'llders should therefore call on their section leaders, and when

0Ilerating independently section leaders should require their

kquad leaders to estimate ranges to the targets whenever a rangetinder is not avuilahle. Experience has proven that single esU-

llllltes of traint:'d men will result in a probable error in range

(h~termination of about 15 per cent, and that the average of the

('~till1ate of several men may reduce this error to 10 per cent.

The'maxlmum error of properly adjusted rang-e finders of the

k('lf-contained base type is 5 per cent. In taking the range

from the map, the error is from 2 to 10 per cent, dependingU[IOnthe methods used und the scale and accuracy of the map.



8G BASIC FIELD MANUAL

138. Use of range finders.-Estimation of ranges in exceSs

of uOO yards ('un not be relied Ullon to produce accurate reo

sults, Range finders, therefore, are of great value to machine

J:mnners. .All nonclHumissioned of!ieers should be trained ill

their adjustnwnt, cat'e, alld use.

139. Fire for adjustment.-a. Meth()d,~ of executin[J {lre.-

(1) To execute fire for adjustment when observation is good,

the gunner opens fire at the estimated range, rolls the strike

into the target by means of the elevating mechanism, sd~

the rear sight so that the line of sighting is 011 the corrected

..trike on the target, Ilotes the sight setting on the rear sight,

und announeps it as the range to the target. All guns al'e

Uwn laid :nul fire is olwned by command of the unit leader.

(2) When the groulld in the vicinity of the target, for anY'

reason, permits no observation or When it is desired to sur-

prise the targl't with fire, the gunner may alljust on a point

which does oft'er observation and whieh is the saIlle lli8tallce

away as tl:e tat'get IJoYpl'oeecding us eX£llllined ill (1) above.

The gunnel' swings his gun on the targ('t When ordered.(3) When l'ngngLg targets in trpcs 01' huilllillgs, fire

adjustment is fit'st applie(l to the ground at the foot of

tree or bUlIding. The range thus determined is taken as the

range to the target. The gunner UlIllounces the runge awl

elevates hi8 gun until laid on the target. I

b. Limltalions.-It must be borne in mind that fire for

adjustment may remo\'e the element of suqlrise Hnd causea betra~'al of position and intention. It should therefore

used only at the longer ranges 01' where surprise is not an

hnIlOrtant elemellt. Pire for adjustment should not be emplo~'ed

against ra{lidi~' lUoving targets and those whil'h can evade fire

for effect during the pause for ohservation and cOl'l'ectlon.

c. Use.-Against llOsitiOlls such as wootls, trenches, or oUlPr

organized at'eas, fire for adjustment should be employed.;It should be the rule to employ fire for adjustment on every

practicable o('('asioll when it promises a more etlicacious fire

effect. "

140. Windage corrections.-a. "The amount by which the

path of the cone of fire is defiected from its normal path de-:

Il('nds upon the force and direction of the wind and the range

to the target. The amount of windage required to correct for

be,

'

"




a 3 o'clock or 9 o'clock wind having a velocity of 10 miles auhour, when using MHlOO,cai. .30 ammunition, with the 150-

grain bullet, for the key ranges is shown in the following

table:10-tnile teind fron~ 3 o'clocl~ or 9 o'clock

Range: Correction (mils)500 11/2

1,000 ---------------------- 41,500 .;.____________________________ 7

2,000 --_____________________________ 10

1). The f'ffect of winds. of other vPlodties or at other ranges

nlay be approximated by an inspection of this table. For

r1rnctical purposes the effect of a wind varies directly as its

force. For example, a 20-mile wind would require twice the

correction. shown for the various ranges. \Vinds that are one

hour away from 3 o'elo{'k or 9 o'dock (considering 12 o'clock

to he the direction of the target) require slightly less wind-age correetion than 3 o'dock or 9 o'(']ock winds. \Vinds that

are one hour away from G o'clock or 12 o'clock require slightly

l~~!ishan one half as much windage correetion as 3 o'clock or

\) o'clock winds.c. In the fire order, windage correction Is announced im-

lliediately after range as .. SIght right (left) 5."

SF:CTION IV

CLASSES OF FIllE

141. Classes of fire with respect to gun (fig. 34).-a. FIxed

fire is that fire in which the beaten zone Is not increased in

\\'ldth or depth by tnlYersing or searching. The elevating

Qnd traversing mechanisms may be clamped so as to limit the

dispersIon of fire. Fixed fire is emplo~'ed against small targets,kUeh as machine guns u('flnitely located, small columns, groups

(If men, bridges, roads, defiles, and trenches.

b. 'l'raversing fire is fire distributed In width by successive

('lIanges in dIrection of the gun. It Is used to engage lines,

trenches, edges of woods, and other areas presenting wIde

targets ..

c. Searching fire is fire distributed in depth by successivechanges In elevation of tile gun. It is emplo~'ed against deep




r

T

targets such as columns, trenches, and edges ~f woods takeVin enfilade.

d. Combined traversing and searching fire is fire distributed

both in width and depth by succeHsive changes in direction and

elevation of the gun. It is employell against oblique targetS,142. Classes of fire with respect to target (fig. 34).-0'

Frontal.-Frontal fire is fire delivered at right angles to the

OIRECl"ION OF

MARC'"'

4z:rua

T T

T

fIXE..D' StAQCHlf1G TRAVI.R5If1<i f120rITAL OBl.lQUE. ~NfILADE. fLAtU\\Ku

~.", ;;QAZI~~-~

Z,'IGl:UE 34.-Classes of fire

tront of the objective. If the target has little depth, such as

line of skirmishers, frontal fire is the least effective type OJ

machine-gun fire since the long. axis of the beaten zone

at right angles to the long axis of the target. Frontal fir

dcli,ered against the head of a column advancing directlf

toward the guns is, however, highly effective fire. This

of fire frequently has to be employed in the attack becausethe fact that the area in Which guns may be placed is limited.

i

clas

o



I

i

I


'\Vhere this area is not restricted, frontal fire may be obviated

b3" Nacing the guns so that their fire will be oblique or flanking.

b. Oblique.-Oblique fire is fire delivered at an objective from

a direction oblique to its longer axis. It is generally more

N'fl.Ctivethan frontal fire because more of the target is in-

elUded in the beaten zone of each burst.

c. Fla,nking.-Fire delivered against the flank of a target

If!<'aIled flanking fire. When the long axis of the target is at

l'ig!lt angles to the direction of fire, as in the case of a section

('O!UTnnttacked from a flank, flanking machine-gun fire is not

"ery effective, since only a small part of the target is coincident,

Ol" nearly so, with that of the beaten zone. On the other hand,

III a skirmish line engaged from its flank, this fire becomes

Obliqueor enfilading (d below) and is highly effective.

I d. En{ila.de.-Enfilade fire is fire, either frontal or flanking,

I in \\'hich the long axis of the target coincides, or approximately

('Olncides,with that of the beaten zone. It is the most effe~-

U"e type of fire. Columns approaching the gun and lines en-

~ag('d from positions on their flanks are said to be taken in

~l1ftlade. Troops taken in enfilade at shorter ranges form the

deal machine-gun target.

143. Classes of fire with respect to ground (fig. 34).-a.

Plun,fJing flrc.-l'lunging fire is that fire in which the angle

Of fall of the bullets with reference to the slope of the ground

(or other object) struek is SO great that the danger space is

Il.11Vroximatelyequivalent to the beaten zone. At the closer

I'll.ng-eslunging fire results from delivering fire downward from

high ground on such ground as lies nearly at right angles to

the cone. Such fire may also result against ground which

1'1!i(~1i sharply to tIle front with respect to the position of the

~Un. At the longer ranges, fire becomes Increasingly plunging

Ill! tile angle of fall of the bullets becomes greater.

b. Gra.zing.-(l) Grazing fire is fire which is approximately

b1tl'UIlelto the ground and does not rise above the height of

nlQn standing.

(2) A band of fire is fire, grazing, at least in part, and

l'C!ferably from the muzzle of the gun to the farther end

It the beaten zone, delivered by one or more guns with

he Mme mission.

. 144. Effect of proper location of guns.-ordinarily the posi-

Ion of the target with resped to the gun ruther than the

98fl53°-32--7



~o BASIC :FIELD MANUAL

shape of the target will determine its vulnerability to fire

For example, a skirmish line engaged by frontal fire is a

target, whereas, if aUaeked from a position on the flank,

may be a good target. As the enemy will never knowing!.

present deep enfilade targets, it must be expected that these Wi

usually be obtained by skillful selection of gun positions.

SECTION V

TARGliJT D"U~SIGNATION

145. Preliminary training.-Before taking up the subject

target designation, maehine gunners must be familiar with tll

military an(l topographical terms emplo~'~d in designating

gets; for example, cre~t, hill, cut, ridge, crossroads, right, let

flank, skirmishers, column, and patrol. The soldier should a1•

be instructed in the meaning and use of such terms as bO

zontal, vertical, above, below, rectangle,' square, triangle, 111

)Oard,and pace. Before practical work in target designation

taken up, a thorough course in visual training and range eSmation should be given. The soldier must be taught.to use }1

eyes 8ml retain mental pktnres of what he sees.

146. Methods of designating targets.-a. Traccr ammU

tion.-Targets may be designated by flring traeer ammuniti

from rifles and pistols. Ritiemen llIay fire tracers to pol

out targets to machine--gun leaders who have just come up"

b. Bursts of firc.-When observation is good, machine gUners who have located the target may fire bursts to

the location of fianks of any enemy target to machine gU

which have just com;::into position.

o. Leader layi1;g the gun.-The leader may lay one or roO

guns on indistinct targets or he may lay one gun and fire

cautioning the remaining gunners to watch his burst. Tb

method usually gives best results, especially when speed

essential.

d. Oral descriptlon.-This is the usual method of designati

targets.

147. Oral designation.-a. Sequenee.-Tlle essential partS

an oral designation are announced in the following sequen

Ran~e.

Dir(~tion.

Description of target.

'

pO

t1

indic1



BASIC FH:LD MANUAL

149. Importance of proper distribution.-Fire, to be effe

tive, must be distributed over the entire target. Imprope

distribution results in gaps between beaten zones and aIlo"-'

a part of the enemy to escape or to use their weapons Ull

hindered. Moreover, because of the compactness and densit)

of the cone, improper distribution will cause wastage of aJll

munition by throwing too many bullets into a part of the tllt

get While the remainder of it is untouched.

NO e ". NO 1I'~GURI;} 35.-Scll:l80rS by section

150. Methods of engaging wide targets.-a. By section.

(1) Soissor8, when the target doC's not exceed. 50 mils

1vidth.-When sections engage frontal targets which do J l

exceed 50 mils, they use the method known as the scisso

method. By this method, each gun lays just outside the CO

responding flank of the target, traverses across to a point j1l

outside the other flank, and back, each gun thus covering tll

entire target. This procedure is continued until the commaIJ

to cease flring is given. (Fig. 35.)

(2) Inlfartt traverse, when. the target meaSures more th

50 mils in. widtn.-By the inward traverse method, each gtl

lays just outside the corresponding flank of the target, travers

across to a point slightly heyond the center, and back to tstarting point. This procedure is continued until the co

mand to ('('ase firing is given. O'ig. 3G.)



BASIC FIELD l\1ANUAL 93

(:3) Swinging traverse, when the target, 8lUJh as cavalry or

Ifantry, is moving rapidly towarit the guns at short range.-

the swinging traverse method, each gunner loosens his,a\'(l"/iingclamp a sufficient amount to permit traversing the

llJ. by placing the weight of the body against the grip, and

~t by use of arms only, and each gun is laid on any portion

; th!~ target, and traversed, firing continuously. This type

. fir!., however, is wasteful of ammunition, and should be used

13'Under the conditions indicated above.

NOlo N01

FIGURE36.-Inward traverse by section

• /)11platoon.-(l) Scissors, 'lellen the target measures less

100 mils in width.-Dy the scissors method, each section

~lijllllycovers its corresponding half of the target as pre-

~bed for scissors by section. (Fig. 37.) The platoon leader

It,' Ilowever, order the right section to cover the left halfhe target, and the left section to cover the right half forfOllowing purposes:

:) ~'o secure oblique fire.

) In order to shoot through a gap in the line of riflemen.C) In order to obtain safety for overhead fire or to avoidhelld fire.

) Inward traverse, 'lclten the target measures more than

tn-flll in 'It'idth.-n~, the inward traverse method, each sec-

~

'"




NOoeO::!O 4

tion executes inward traverse on its corresponding hulf of

target, or the platoon leader may order the fire of the secti

to be ('1'o8sed, as explained in (1) ahove. (I<'ig.38.)

FIGtJRI<: 37.-Scil;sors by platoon'

151. Methods of engaging targets takt'in in enfilade.

Gencral.-"Ko enemy will knowingly'present an enfilatle t!l

to machine-gull fire; but if lie does happen to present st1e

N04 NeZ. N01

FIGt:RE 38.-Inwurtl traverse by platoon, showing croHslng'

of fire of sections to secure oblique fire

tar~et, he will qUickly (kploy when fired upon. lIence

method of engaging enfilade targets, to be etncient, must be

which can be quickly and readily applied. Further!ll

~



i


Ilners must be trained to follow any changes in formation

~<leby the enemy after the initial bursts of fire•

• [l1ixed fire.-Targets. having 'little depth and located on

r"er ground at short ranges can best be engaged with fixed~. The depth of the beaten zone ,vill ordinarily be suf-

ent to cover effectively enfilade targets of this character.

the ground is rising to such an extent that the beaten zone

°Ines shorter than the depth of the target, searching will

I'eto be used.' ,

o.8carchingfire.~(1) By sectiCJn.-Targets having consider-

lie (l<~Pth,or located at ranges such that the beaten zone of

inl11vidual gun is shorter than the depth of the target, may

e1lg-ag{>dy a section as follows:

]'(0 eo

C) . . . . - - - - - - - - =4OJ r

FIGunE 39.-Sectlon engaging n depp ('nfilade target

(Q) If "t.he target is stationary, h~s limited' niobility, or is

o\'ingslowly, the gunner of No.1 gun la~'s on the near end

bd !Searches up; the gunner of No.2 gun lays on the far end

1<1 searches down. (Fig. 39.) ,

I:b) ,If the target is moving ~apidly' away from the guns,

h gunners lay on the far end and search down.1(0) If the target Is moving rapidly toward the guns, botll

llners lay on the near end and search up.

~2) By pla.toon.-A platoon uses the same method as the

otlon, each section engaging the target as if it were actingIle. In case it becomes necessary to switch the fire of one

,tton to another target, the original target Is thus covered

4the remaining section. ,

. 4rnount Of search.-In case the conditions of the ground

IQ \>i8ibllity are such that the gunners will be able to st>e

strike of the bullets, the amount of search should not be

en. The gunners keep' their fire on the target as they

:I'Ch hy observation. If, however, the strike can not be seen,

I

amount of' search may be prescribed. The following 'rulethe 1\11900ammunition (150-graill bUllet) may be used to

el'tnine the proper number of mils of search:

(1) Measure or estimate the depth of the target in ~'nrds.

~

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~



96 BASIC FIELD MAKUAL

(2) Divide this b~' the number of yarus change in rll

caused b~' a change in plevation of 1 mil for the range to

center of the target. This Uivisor can be estimated froUl

fonowin~ table:

nange:

1,000_____________________________1 mil pquals 30 yll1,::iOO 1 mil equals 20 yll

2,000 1 mil equals 10 yll

NOTE.-The fi~res are based on ll'ngths of beaten zones sho"

Figure 33; allowances must be made for the effect of position and

For example: An enprny column, estimated to be 200 yards long, Ifilllded by a section of guns at a range of 1,000 yards. 'l'he col

coming down a gl'ntle tllope. The proper amount of search shoU

6 or 8 mUs (200/30 equals 7 mUs).

--<....

- --ROt. 00:::_

NO 1

- ~}<'IGVRE0.-Sectlon engaging a short oblique tar-

get (using section scissors)

152. Methods of engaging oblique targets.-a. If the

of the target is less than that of the beaten zone, a secti0platoon uses the seissors or the inward traverse method,

l)('n~Ungon the width of the target as seen from the guns.

-tt:: ....

:::~._-FIGVRE41.-Sectlon engaging a long o1Jlique target (uslna'

inward traverse and Sl'arching)]

rule that not more than 1)0mils of front should he ass

a single gun determines which method will be used. (I\'ig:b. If the depth of the target is greater than the beaten'

combined traversing and searching must be used. Sdssotinwa I'd trawrse is combined with searclllng. (Ii'ig. 41.)

uJl

(

_ __ - ~ •

~

l




l153.Methods of engaging point targets, or targets cover-

I~El1ll.allreas.-a. If the target is clearly visible and will be

I~lI(h'd in the beaten zone of a single burst, and if the range

,:ceUratelYknown, fixed fire may be used.I . If it is desired to cover a relatively small area in the

bClnity)f some object such as a bush or a tree, and it is not

\tfSlbleto define clcarly the limits of the area so that the

fSSOl'S method can be used effectively, the area may be cov-

d by a section fiS follows (fig. 42) :(1) The section leader anno~nees the total amount of trav-

8e and search, if search is neeessary. Each gun la3's on,e Ohjeet used as an aiming point, or on the center of the

(lQ to be covered. The right gun of the section traverses

No 1 GUM

FIGURE 42.-:;\lethod of eugaging small area target

the right one half of the announced traverse, searches up

lnllH, then traverses left the full amount ordered; it con-

~ueH to search up 2 mils at a time, and traverses the entire

11th of the area until the upper half of the total area has

n (~overed; it thpn sefirclles down and traverses, covering the

Itire area. '1'he left gun starts traversing to the left, and,

!ItChingdown 2 mils at u time, covers the lower half of the

~!U before searching up and traversing to cover the entire

t'eI'U, The operation is continuous until the command to cease

In~Is given.(2:) If it is desired to cover such an area with u platoon, the

ltul amount of traverse and search is ordered us above. Each

letton covers the entire area exactly as if )t ,,~ere firing

lon(); this requires but oue method of operation for the In-

, \'hlunl guns.(3) If it Is evlc1ent that the target is beyond, short of, or

Oll(! side of, the selected aiming point, or if the ground af-

Il'd~ observation of shots striking short or over, or to one

lle, it mllY be advisable to order the trayerse or search, or

'




both, only in the direction likely to produce hits .. The or

may therefore be in one of the following forms: "Traverse

search up 8"; "Traverse Hight In, search 4"; "Traverse

24,.~earch down 4."(4) Becnuse of the depth and narrowness of the bell

zone, the proper amount of search will usually be much

than the traverse.

154. Combined sights.-a. General.-(l) Combined sl

i~ a method of engaging a depv target hy means of twO

more guns which Use the same niming point with (lifferent

vaUons set off on the rear sights. 'This proeedure maYemplo)"ed as well to insure hitting a target whose exact I'll

Is not known and which might be lost if fire for. adjustll

were used. Guns laid with combined sights. may fix, seH

or tra verse.

(2) Comhlned sights should not be regarded as a cure-all

poor range determination and poor Observation. It Is relati

wasteful of ammunition, since, as a rule, only part of the C

bined beaten zones is actually placed oil the target.

hined sights shOUldnot he used unless thh~ additional expc

ture Is warranted hy the impossibility of accurate runge

termlnation~ the lack of good observatioll, the necessity of

prise, or a eombination of these conditions. lIenee it is usl1

inadYisable and unncecssary to use this method at close raIl

Guns which are short and over the target are adjusted at 0when visibility permits. .

b. By 8cction.-Hanges announced will differ by 100 ya

The leader determines the range to the target. The range g

the base gun Is GO )'ards less than the determined runge'

the range for the other gun is 50 ~'ards more thun the

mined rUllg-e. .

c. BJI platoon.-Tlle lllatoon uses the Sllme method as

sedion, except thnt the range for the base gun is 1GO

less than the determined rUll~e; No.2 gun, GO yurds less;

gun, 50 )"urds more; and No. 4 gun, 150 yards more .•

e.xample, ~he range is determined by the platoon leader t

1,3:>0 ~"urds. !\o. 1 lays with .1,200; No. 2 with 1,300;with 1,400; and No.4 with 1,GOO. .

155. Use of auxiliary aiming mark.-The use of the all

ary aiming mark 1s essentially Indirect laying and is inchi

here because of its close connection with direct laying.

]Iar. 3 f, Part Two.)

J

de

y

~

:N



f

BASIC FIELD MANUAL

SECTION VII

99

OVERHEAD FIHl~

156. General.-a. Overhead fire is fire delivered over the

heac}:'! of friendly troops. A machine gun is capable of deliver-

Ing this tnle of fire because of the small and uniform disper-

Io;10n of the cone of fire resulting from the use of a fixed mount.

The use of overhead fire increases the radius of action of the

machine gun, since the latter is not confined to positions on

line with the troops that it Is supporting but can utilize posi-

tiollS

in rear which afford a fuller use of the fire pO\ver of

the weapon. In the attack, the use of overhead fire permits the

machine gun to give support during the advance of rifte units.

FIGURE 4:3.-Componpnts of minimum clearance

b. Overhead fire may be delivered by either direct or indirect

lll~'fng. This section will deal solely with OYerbead fire de-

, livpred by means of direct laying.

157. Minimum clearance.-The center of the cone of fire,lnUlo;tbe a certain prescribed distanee above the feet of the

troops over whose lletHls tire is to he delh"ered. This distanee

Iii known as the" minimum dearanee." (Fig. 43.) This re-

, fIUired cll~aranee, usually expressed in mils, is found by adding

together the following elements:a. The height of a man standing, taken as 2 ~"ards.

1J. Half of the vertical dimension of the 100 per cent coneot fire lit the range of the tl.oops. (l~ire-eontrol Tables, Brown.

Jng 1\Iachine Gun, caI. .BO, 1\11917.).

c. A margin of safety of 5 mils or the number of mils sub-t<mded by 10 feet at the range to the troops, whichever Is

gl'eater.d. An nddit10nal allowance to compensate for a 15 per cent

,error in range tleterminntion.158. Safety angles.-a. III ol'ller to obtain this minimum

Clearance,' the center of the cone of fire which would strike




the feet of friendly troops would have to be elevated throngb

nn angle equal to the minimum clearance expressed in mils.

This required angle is known as the "saft'ty angle." rflle

~afet~. nngle for <lir'eet IUJ"ingis thus seen to be the difference

between the angle of elevution required to ohtain the minimunr

clearance, and the angle of elevation requiI;ed to hit the feet ofthe troo))s.

b. The safet~. angles for all ranges on level or uniformlY

sloving ground have been computed and are contained in r"ire-

('ontrol Tables for Browning Machine Gun, caliber .ao, modelof 1911.

FIGURE 44.-Application of gunner's rull~

c. To Jl('rmit overlwad tire on any target, the cone of tire.

must pass over the hl'ads of friendly troops by at least theminimum deurance. In order to have a quick and simple l

means of insuring this condition, two rules of thumb huve

been devised by means of whieh sufety angles may be meas-

urcd with thc rear sight. Th""c rulcs arc ""rrcct only for jthe :\IH)OG ammunition (15O-grain bUllet). ,

159. Gunner's ntle.-Tlle gunner's rUle is designed for use

in ('a~e the range to the target is equal to or less than 900..;

~'ards. It Is ar1plied by the gunner unless the sufety

has been detel11l1ned un!l announced by the section or platoon

leader. The rule is as follows (fig. 44) :

a. Lay the gun on the target with the correct sight settingto hit the target.

b. 'Vithout changIng the laYing of the gun, set the rearsight at 1,525 yards. .,

o. Look through the sights and note the point where thisnew line of sighting strikes the ground.

limit-

,



BASIC FIELD MANUAI. 101

d. If this point is ahead of the feet of the friendly troops,

O"erhead fire can be safely delivered until the troops reach it.

e. If this point does not clear the feet of the friendly troops,

It is not safe to fire.160. Leader's rule.-The leader's rule is used by the platoon

orSett!on leader only in case the range to the target is greater

than 900 yards. The rule is as follows (fig. 45) :

a.• Lay the gun on the target with the correct sight setting

to hit the target.

b. Select a point on the ground to which it is believed

f1'1(llldlyroops cnn advance with safet~'.c. Accurately dptermine the range to this point.

I

II~-

'--TQ.OO,P5

1000 YAIU)5

1~OOYAR.D::l--

FiGUllE 4;'i,-Applicution of h'uder's l'ule

d. 'Vithout disturbing the laying of the gun, set the rear

~Ight at 1,525, or the range to the selected point plus 650,\\'hlchever is greater.

c. Note the point where the new line of aim strikes the

~rOuIld.

(1) If it does not clear the feet of the friendly troops, it is

!lotFlafe to fire.

(2) If it strikes at the selected. point, the selected point

Illal'ks the limit of safety.(3) If it clears the feet of the troops and strikes short of

the Flelpcted point, it is 110t safe for the troops to advance to

the Flelected point, but is safe at least to the point where it

~tl'lk('s.

(4) If it clears theseleeted point, it is safe for troops to

lld\'ltIleeat h~ust to the select(~d point.

f. Continue to test points I'(hort or beyond the first selected1l01lltuntil the line of aim and a selected point ('oinelde, which

1ll11I'ks the saf{'ty limit.

~

-- -

-- -- - -- -~

'



102 BASIC FIELD :MANUAL

161. Procedure before friendly troops reach limit

safety.-a. Safety limit identified on the ground.-The safe

limit having been determined, the gunners and all leaders

note some terrain feature by means of which the limit mayidentified on the ground. In case safety has been determined 11

the platoon or seetion leader, the limit of safety is announC

so that the gunners and squad leaders are able to identl

it; if ncel'ssary, the limit is indicated with the rear gig

of each gun, being careful not to change its laying on ttarget.

b. Report by gunners.-In case tbe gunner's rule is appliegunners r{>port "clear" or "not clear" to indicate whether

is safe to fire.

c. Checking laying 'while firing.-After determining or noti

the safety limit, the gunner runs the sight back to the ran

to the target in order, while firing, to check the laying <?nttarget.

162. Procedure after friendly troops reach limitsafety.-a. Unless otherwise ordered, when the fr.iendly troo

reach the limit of safety, gunners cease firing.

b. If it is desired to search the area in rear of the target, t

section or platoon leader announees a new range and orde

Search the rear area. The range announceu is 1,525, or the raIl

to the target plus 650 ~'ul'tl:,;,whichever is greater. Gunnel

set their sights at the range annoulleed, and, keeping tlJline of sighting ahead of tile feet of the friendly troops, elevll

their guns by a series of 2-mil lifts until their sights are

on the target. In case the friendly troolls can not be seen, tgun is lifted at once to the target with the sight setting

. llounced.' Each gun covers the same front it covered

firing 011 the target. The medium or slow rate of fire

be used to ('onserve ammunition. 'Vhen the friendlyreach the target, gunners ('ease firing. .,

163. Use of :field glass in applying safety rules.-It

frequently desirable to determine safety for overhead

before guns are placed in position. Safety may be appro

mately determined by means of. the inverted sight leaf in

t~'pe EE field glass. After the guns are emplaced, safe

f;hould be checked, where Ilossible, with the gun sight

(Pto Two, eh. 1, Sec. III.)

,

n1\l

allgne

a

wllt

sho\1

troo

:t

t

'




164. Troop safety zones.-lt may at times be imperative to

deliver overhead fire, if actual safety does exist, even though

the gunner's or the leauer's rule inuicates that it is not safe

to fire. Such conditions will usually obtain only when the

target is at a long range, and the guns, troops, and targets are

at about the same elevation. To cover such cases, the following

table of troop safety zones for the 1\11906ammunition (150-

grain bullet) has been worked out. It will always be safe to

deliver overheuu fire by direct laying at the ranges indicated

it the troops are within the limits shown, unless, of course,

they are above the line gun-target, when it will not be possi-ble to use uirect laying. .All ranges must, however, be accu-

rately determined.

:Range to target (~1arus): Troopsare safe from-1,400________________________________ 500 to 600 yards.1,mO_______________________________ 325 to 825 ~'arus.

1,600 .. 275 to 9GOyarus.

1,700________________________________ 225 to 1,100 ~'ards.

1, 800_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 200 to 1, 200 yards.

1,900________________________________ 175 t,o 1,325 y~rds.2,000 150 to 1, 425 yards.

! 165. Precautions for overhead fire.-The following precau-

tions will always be observed when overhead fire is used: .

a. If safety has been checkeu only by application of theleader's or. gunner's rule, overhead fire will not be delivered if

the'troops are less than 300 or more than 1,800 ~'ards from the

guns, unless the vertical interval of the troops below the line

gUn-target Is sueh as to make safety obvious.

b. A barrel that has fired 5,000 rounds or which gives evi-

dence of excessive muzzle blast should not be used for overhead

fire.c. The tripod must be firmly mounted and wherever prac-

ticable should be snndbagged; badly worn tripods will not be

Ul'led.

d. The water jaeket must l,e kept filleu, anu guns not allowed

to heat excessively. .

c. Depression stops should be used to prevent the muzzle

of the gun from being accidentally lowered below the limit of.Flnfety; the neecssities of battle, llowever, may prevent the u~e

of this precaution.

-

-




f. Overhead fire must not be delivered through woods whichare likely to deflect bullets into friendly troops.

g. Friendly troops should be informed when fire is to be

directed over them.SECTION VIII

l<~IX.AL PHOTECTIVE LIXES AND SI~JCTOUS Ol<"' FLUE

166. Definition of final protective line.-The final protective

line of a machine gun may be defined as a predetermined linf'

nlong whith, in order to stop assault.'?, it is intendcr]; to place

graZing fire, fixed a."! to direction ana elevation, and capa7J7cof(ldivenl under anycondifion.fJ of '/.;..;,sibility.

167. Sectors of fire.-Front-line machine guns on the de-

f{'IIl;;iveare assigned sectors of fire, the inner limits of wIlich

are usually, but not always, the bands of grazing fire delivered

along the final protective lines. 'fhe machine-gun fire unit is

re~ponsible for engaging the enemy within its sector, subject.

in~ him to fire as he approaches, and finally forcing him topass through coordinated bands of grazing fire before he canueliver his assault.

168. Influence of terrain.-On level or uniformly sloping

ground up to a range of 700 yards the lower part of the com'

does not rise above the height of a man standing at any point

'from the muzzle of the gUll to tIle point of ll11IJllct. The length

()f the farther half of the beaten zone should be added to therange, 700 ~'ards, making the total possible danger space, on

level or uniformly sloping ground, apvroximately 775 ya'rds.

(These figures are for the 150-grain bullet, l\IWOG ammunition.)

The great length of the danger space on such terrain is the

most imllortant characteristic of machine-gun fire with refer-

ence to the final vrotective line. However, ground that slopes

uniforml)' for 700 ~'ards or level stretches of that .length are not

often found. Three cases are given in the following para-

graph to illustrate the different types of terrain on which final

pl'ote(.tive lines ma)' have to be placed and the methods of

laying the gun for elevation and direction in order to get the

maximum alllount of grazing fil'e in each case.

169. Methods of laying on final protective lines.-a. Lay

tlte gun for direction by sillJ{llysighting in tlte desired direction.

b. Obtain proper elemtion ns follows:

(1) Case 1.-1t tlte ground is level or slopes uniformly for

a distance of 700 ~'ards from the gun, select a point at a range




of approximately 700 ~oarodsand, with a sight-setting of 700

3°ards, aim at this point.(2) Case 2.-If the ground slopes uniformly for a distanee

less than 700 yards, select an aiming point, such as a bush,at any range along the slope. Aim at a point on the object

about the height of the gun, using a sight setting of 700 ~oanls.

The fire will be grazing only as far as the break in uniform

8lope.(3) Case S.-It is possible to place grazing fire on the re-

'Verseslope of the hill if the shape of the ground approximates

the curve of the>trajectory at the range to the slope. If it isdesired to place a final protective line on such a slope, lay

the gun on the crest with a sight setting to hit the crest, and

tlwn elevate the gun three mils, in order to clear the hill with

the lower half of the cone. For the average ranges used in

final protective lines fire-control tables show that 3 mils will

Usually cause the lower half of the cone to clear.

c. Whenever the tactical situation permits the laying should

lie verified by firing.it. If a depression exists between the gun and the ground

On which the final protective line is placed, the depression is

dead space in the band of machine-gun fire, and must be cov-

ered by other weapons.170. Laying gun at night and during fog or darkness.-a.

The gun having lwen laid by any of the foregoing methodsof direct laring, provision must be made to enable the squad

to lay the piece when under a sereen of darkness, smoke, or

fog. The following simple and efficient methods are avail-

able, data by both of which should be obtained and recorded:

(1) First method.-The gun having been properly laid for

direction and elevation, zero the dial, clamp it, and then

Jlleasure the quadrant elevation-that is, the angle above thehorizontal-with a clinometer. Thereafter, to lay the gun at

any time, turn the gun until the index on the pintle is op-

llosite the zero mark on th(>.traversing dial and b~' means of

n clinometer set the recorded quadrant elevation on the gun.

(2) Second, method.-The gun having been properly laid

for elevation and direction, place an aiming stake at a short

distance in front, but offset slightly from the line of fire.Without disturbing the laying, manipulate the rear sight until

a line of sighting is obtained on a designated mark on the

{)8!)!):l°-32--8



l OGBASIC FIELD :MANUAL

aiming stake. To lay the gun properly at any t~me, set the

sights according to the readings prpviously recorded and aim

at the mark on the aiming stake. This method is less aC'

curate than the first, but enables fire to be delivered in casethe clinometer is lost or broken.

b. The determination and application of data by these meth'

ods are essentially indirect laying and are included here uecause

of its close connection with direct laying.

171. Procedure in firing.-a. Rate of {ire.-The normal rate

of :fire on a final protective line will be "rapid" (250 rounds

per minute). Successful protection of a position will dependto a great extent upon the intensity of fire. 'Vhen the two

guns of a section are assigned the same final protective line,

the section leader must so coordinate the fire that the maxi-

mum usable rate is obtained and at least one gun is alwaysfiring.

b. Type of {ire.-li"lxed fire will be used along a final protec-

tive line. This will insure dense and continuous fire. Gunnersmust be taught that once fire has been ovened on a final protec-

tive line, their mission Is to keep as great and as nearly a con-

tinuous stream of fire on that line as possible; any deviation

will result In uncoveling a portion of the line, and the enemy

assault may pass through this gap without sustaining losses.

ThIs rapid tixl'd fire is maintained until the assault has been

repulsed or the position has fallen. Guns are then shiftedto the most dangerous target.

SIWTION IX

nANGE CARnS

172. Defense range cards.-a. General.-(l) In order to be

prepared, on the defensive, to deliver fire promptly, firing data

should be determined to all key points, such as crossroads,

ridges, stream junctions, woods, and other landmarks within

the sectors of fire at, or near Which, targets are likely to

appear. These data must be recorded, to serve as a guide to

the gunners and section leader.. A range card for each gun

is used for this purpose. It Is usuaily in the form of a sketch

of the sector, shOWing only the probable locations of targets

and the data as to direction and range, or elevation, necessaryto plnce fire on these points.




(2) The employment of range cards allows decentralization

()f command without loss of fire control. This advantage is

especially evident in highly organized defensive positions where

guns may be widely separated. Range cards are also of great

'Value in planning the cpordination of defensive fires. Dupli-

cates of the original range cards prepared during the occupa-

tion or consolidation of a newly occupied position are collected

by platoon leaders, who consolidate them for their units.

With the addition of such brief explanatory remarks as may

be necessary, these reports are sent back to the company com-

lnander. Such reports show exactly what the guns can do and

In(licate :where coordination and rearrangement are necessary.

b. I'rclJaration of.-(l) Hange cards should be prepared im-

lllediately upon occupation of defensive positions and copies

Sent to the next higher commander. The defense cards form

a record for the use of relieving gun teams, and are alwa)'s con-

sillered as part of the orders for a position. Range cards

sllould be prepared in advance for nIl' positions, including

alternate and supplementarY positions.(2) In preparing range cards, the following should be taken

us guides: .,

(a) Notation should be made of the accurate location of the

gun posidon, and the position named or numbered.

(b) A means of orienting the card, either by magnetic north

or by reference to prominent terrain features, should be

provided. . ,

(c) All data allli instructions ~hould be legibly printed.

(eZ) Landmarks or targets should be indicated by conventional

signs or sketches in perspective, naming them where necessary

to prevent misunderstanding. .' ~.

(e) Targets should be numbered from right to left.

(f) The final protective line, which usually forms one limitof the sector of fire, should be taken as a base line, with it dialsetting of .zero. That part of the line which provides fixed

grazing fire should be shown in heavy black.

(g) The directions to all targets should be indicated by the

proper dial settings and the elevations by the proper sight

settings and quadrant elevations. (See (3) below.)

. (3) Whenever possible~ Indirect laying data should be pre-pared for all guns, even though they are sited primarily for

direct la~'lng. These data determine the direction to the points

"

'




selected as probable locations for targets, and the correspond-

ing quadrant angles of elevation; that is, the angles of eleva-

tion above or below the horizontal. Paragraph 170 outlineS

the proc('dure required to establish a gun on its final protectiveline under any conditions of Visibility. l\Ietlwds exactly sim-

ilar to tho:-;e given therein may be employed in securing the

data required for all key points in the sector of fire. The fiual

PI'otN:tive line should be taken as a base line to which the direc'

tions of nIl other targets are referred. 'Vitll the gun estab-

FIGl"RE 46.-Range card No.4 gun; 2d Sec., Co. D, 1st Inf.

Jislwd on its final protective line, the dial is zero~d. The gun

is then laid successively to hit the points selected as probable

targets; for each point the dial reading and the quadrant angle

of elt'vntion are recorded on the range card. If the target l1US

width the dial settings for both flanks are recorded. There-

aftN', if it is desired to fire on any of these poInts, the dial reud-

Ing um} the quadrant angle of elevation are announced asfollows: "Dial 5,820, QJ~ Vlus 58" or, If range cards have been

prf'vured, fire is ordered by simply announcing the targetnumlwr.




(4) Figure 46 1S an example of a simple type of range card

)1' Use in defense. Such cards may he prepared immediately

FIGURE 47.-Range card No.2 gun; 1st Sec., Co. D, 1st Inf.

Ifter the occupation of a position. They are replaced as soon

Is possible by others similar to that shown in Figure 47, which

~i\'l~S the data for both direct and indirect laying.

1400 0

1100 300

700 700

100

o 1400

\~~,~ rAl(NH'tOU5f'

. ~~.-::'

INITIAl.. GU/'(P051T10J \tOOYA~M~T Of )10USf.ON D~ey RI~~

FIGURE 48.-Type of attack range card

173. Attack range cards.-No fixed form of attack range

card is prescribed. Figure 48 shows a suitable tn>e. The

rallges are measured from the initial gun position, using a

rUllge finder or map wherever possible. The range card en-



110BASIC :nELD MANUAL

abIes the gunner or section leader to determine quickly tl1

range to the enemy position, at any time during the advanC

by interpolating between the measured ranges to the ke.

points. It is Usually not necessary to indicate directions 0

quadrant angles of elevation on an attack card.

SECTION X

FIRE CONTHOL

174. General.-a. Fire control of machine guns Implies tb

ability of the leader to open fire at the Instant he

adjust the fire of Ills guns Upon the target, shift it from

target to another, regulate its rate, and cease firing at will.

He must be able to do all of these things pI'omptly if tbe

fire is to be E'ffective. Lack of proper fire control results

loss of surllrise effect, premature disclosure of position" miS'

application of fire on unimportant targets, loss of time i~

securing adjustment, and wastage of ammunition. Fire coil'

trol is then-fore a bighly important phase in the techniqueof direct laying. ,

b. }~ire control is based primarily on diSCipline, and second'

arily on correct technical training. Inasmuch as machine-gUll

Sl.'Ctions are fr~'quently S<,parated by Wide intervals, control

must often be decentralized .. To this difficulty are added the

excitement and noise inCident to firing an automatic' weapol1.

Under th('se conditions goot! fire control can be had only if allmen are WE'lldisciplined and llave the proper technical trainingto carry out fire orders promptly.

175. Chain of fire control.-a. The company commander

gives his ord('rs orally directly to the platoon leaders or trans'

mits written orders to them by messengers. These are tacticnl

orders which rarely prescribe the tecllllique to be employed in

('arr~'ing them out. The actual control of fire' is thus left tothe platoon leaders. As a rUle, the latter give their instructionS

orally directly to the section leaders. Section leaders may be

:ts8embl~d, under Cover, for this purpose, or the platoon leader

may go successively to the section leaders and give them im]i.

vidual orders. If the sections are Widely separated, as theY

may be in the defense, it may be necessary for the platoon

leader to send written instructions to section leaders.' IIe willrarely be able to issue orders orally to hi~ entire platoon oncefire has h{,(,ll-oppnf'd.

desirc~!

oll

i



BASIC FIF..LD :MANUAL 111

, b. Section leaders use similar methods in controlling theIr

~qt1UdS. They should post themselves in positions from which

hey can observe the fire and where they can be seen by the

o.2 at each gun. Before fire opens their orders will as a rulee oral. While firing is going on, signals (alone or combined

IVithoral orders) will usually have to be used for the control

ot fire. It will frequently be necessary for the leader of

a section to go to the guns and give orders directly to the gun-Iers. This method is especially applicable wben new and

lnexpected targets appear after tbe unit is engaged.

o. Witbin the gun squad, the squad leader is responsible fornre control. When ordered to do so by the platoon or section

euder the corporal fires the gun. This will often saye time in

the transmittal of orders for the occupation of a position and in

the designation of indistinct or poorly defined targets, and in

~(~mecases will give greater assurance of effective fire. The

cO/'poral may fire whenever, in his opinion, it is necessary

to do so in order to bring effective fire speedily on the target.\\"henthe corporal does fire No.1 assists him in the observation

flnd adjustment of fire and No. 4 becomes responsible for

l\mmunition supply. When not firing the corporal posts himself

~oas to be able to observe the fire of the gun and at the same

time close enough thereto so that he can shout his orders to

the gunner. The corporal does not look to the rear for signals,

but concentratps on the observation and adjustment of fire.Observation and adjustment of fire on the proper target is the

ltJost important fire-control duty of the squad leader. It isthe duty o'f No.2 to watch the section leader for signals; he

can not do this if be observes the fire. Ill' transmits all orders

to the gunner or the squad leader.

176. Adjustment of :fire.-a. Observation and adjustment of

6re Is the most important phase of fire control. Itmust beeOntlnuous throughout the action. The gunner must be trained

to observe and correct his own fire without command and to

('heCkhis laying from time to time. Ill' should also be in-

fitructed to anticipate the action of the enpmy after fire is

0PNletl, shifting his fire to cover any changes in the formation

Or location of his target. If he fails to do these things, the

Qqundleader must check him and this responsibility continues11D through the platoon leader.

b. Corrections are announced or signaled as "Up," "Down,"

"IUght," or "Left" so many mils. Small changes in elevation.




such as Up 5," or Right 2," are set off on the elevating haJJ

wheel or the windage scale. Large range corrections are ml1l1

by announcing or signaling a new range. Signals are prescribe

in Basic F'ield Manual, Volume II.c. 1Vl!ere it is not Possible to get observation of strike, trace

ammunition may be used in the ratio of 1 tracer to 10 balls.

SECTION XI

:FIRI'] ORDERS

177. Purpose.-A machine-gun leader, 11aving made a

decision to fire on a target from a certain position, conve~'s tblS

information to his subordinates in a combat order. In

to the tactical setting and decision, however, 1ih~ leader must

give certain technical instructions as to how the target is tit

he engaged. These technical data may be included in the

bat order of the leader, in which case they correspond to part

of paragraph 3, or they may be given subsequent to the issuance

ef the. comhat order. In either case the technical data by whic!J

the fire of the section or platoon is c011tro11e(1orm the fire order.

178. Basic elements of fire order.-A fire order contaiJJs

three basic elements, which are announced or implied in everS

case. Only such parts of these will be included as are essential,

but the sequence must alwa~'s he as follows:

Target-designation element.

Fire-distribution element.Fire-control element.

G. Target-desigltfltimll elcrnent.-(l) The target-designntioJ1

element implies ability on the part of the leader to point out tbl'

target in such a manner that gunners ('IU l pick it up readilY,

The leader may lay one or both guns, fire a burst from one of

the guns, or give an oral description.

(2) An oral descrirltion consists of an announcement of tIlt'

range, the direction, and a description of the target, where nee'

l'ssary. For example, the target-designation element would beas follows:

(a) Hange noo.(1) To your right front.

(c) Enemy skirmish Ifne.

fl. Fire-di,sfribufion, elcment.-The fire-diiitrihutionincludes the subdivision of the target, if necessary, and the type

of distribution. :For example: A IJlatoon leader desires to crosS

" "

tactiCO

o.t1ditiol

coUl

elf'l}}(}




Ie fire of his sections on a frontal target, using the scissors

lethod; the distribution element of his order would be as

)llows:

(1) 1st section, left.

(2) 2d section, right.

(3) Scissors.

o. Fire-control element.-The fire-eontrol element may

\~lUde-

aute of fir~.

l'irne of opening fire.

COlumandor signal to commence firing and cease firing.(1) Rate of {ire.-The following are the prescribed rates of

re; unless otherwise specified, the rapid rate will be used.

Slow, one-quarter box per minute (GO rounds).

h1Pdium,one-half box per minute (125 rounds).

!tUIlid,one box 'per minute (250 rounds).

(2) rime of opening fire.-( a) It is often of great importanee

~I.tmachine-gun fire be withheld until the proper moment to~eUremaximum effect and that all guns open at the same

l~tunt. The greatest surprise and shock effect are thus ob-

lined. To insure this condition, the leader may preface the

0tnrnand or signal for commencing fire by the words "At my

Ignat This permits him to check all guns to see that they

re properly laid, or, in case of overhead fire, that there is

tn('i(~ntclearance, and enables him to hold the fire until the

lticalmoment.

(b) Oommanl1 or 8ignal.-lf fire is to be opened immediately,

ne command At my signal is omittell, and Commence firing is

nOUllcedimmediately after the other elements of the order.

Unnel'sopen fire individually as soon as laid.

179. Examples of fire orders-a. Many fire orders will con-

I~tof only the simplest expression of the three basic elements,r one ()r more elements may be omitted. Examples are given

elow:

l]J:urnple 1:

Range 900.

3T-mm. gun.

Commence firing.

FJ;ranlple 2:

Range 1,000.

Commence firing.

"




b. In case separate missions are assigned individual gO

or sections, the order may be as follows:

"No.1 (or first section)-900.

Near end.

No.2 (or second section)-1,100.Far end.

Inward traverse and search.

Commence firing.

c. An order callIng for overhead fire may be in one of t

following forms:

(1) It the range is less than 900 yards-Range 850.

To your left front.

Crest of small knoll.

Scissors.

Overhead.

At my signal.

Commence firing.(2) If the range Is greater than 900 yards-

Range 1,200.

To your front.

Target, edge of woods.

Inward traverse.

Overhead.

Friendly troops in the draw to the front.Safety limit that line of scrub brush [pointing].At my signal.

Commence firing.

(3) If It is desired to search the area in rear of the tar

after the troops "have reached the limit of safety, an order

thIs form may be used:

Suspend firing.1,850.

Search the rear area.Slow.

Commence firing.

d. In case fire for adjustment is used, the order may befollows:

No. 1-900.Sight right 3.

Point where road enters woods



BASIC FIELD MANUAL

Adjust.

Commence firing.

115

All guns-975.

Edge of woods.

Inward traverse.

Commence firing .

. e. WHen firing with combined sights, the difference ln range

~ay be applied by individual guns or by section, as follows:

l!JJ)(lmple 1:

Combined sights.

No.1, 1,000.

No.2, 1,100.

No.3, 1,200.

No.4, 1,300.

To you;' right front.

Target, large clump of bushes.

At my signal.

Commence firing.

1iJJ)a.mple 2:

Combined sights.

First section, 1,250.

Second section, 1,350.

Enemy column.

At my signal.

Commence firing.

1. A small area in the vicinity of a given point may be

~eredas follows:

Range 1,200.

To your left front.

On slope of hill.

Lone scrub pine [pointing].

Traverse 12.

Search 4.

Medium.

Commence firing.

fJ . An especially difficult target may call for a lengthy order

IllliIl1rto the following:

Range 1,100.Sight left 6.

To your right front.



I l G BASIC }'IELD MANUAL

Reference-lone pine.

To the left-small scrub oak.

Left 20 mils and beyond.

Corner of ditch.

Enemy machine gun.

Traverse 8.

Search up 4.

Commence firing.

S~:CTION XII

DIHECT LAYING pnOnLI~MS

180. Purpose and scope.-Direct laying problems are techJ1i

cal exercises designed to instruct officers amI mf'n of mnchill

gun units in the application of the technical methods of <lirer

la~'ing under simple tactical situations. No tactical

are required in these exercises, and the tactical s(.tting shoU l1

be nothing more than a background for the demand for IlIII

chine-gun fire on a given target. The requirement may \'

simply the fire order, or the fire order and actions of the ullil

either with or without actual firing.

181. Preliminary instruction.-Preliminary instruf'tion J}l~'

be given with the situation pre:-;ented by means of a blac~

board sketch, a chart, or a landscape target. Each proble11

should be carefully explained, and a reasonable time alloWel

for its consideration. The required fire order, and, where tl

propriate, a statement of the actions of leaders and gunne:

should then be demanded. The manller of delivery of tb

order as well as its correctness should be noted and commente

upon. All leaders. are thus taught to deliver fire orders wit

confidence, in a sufficiently loud tone of voice, and with dell

ness and brevity.

182. Examples of fire-order problems.-a. Pro1Jlern No.1.

(1) Situation.-A machine-gun section on outpost duty 0

serves a patrol of four 1I1enat A. About 150 ~'ards in its rell

are two columns of files of 10 men each on the two sides

the road. The columns are partly protected by the stone Wtll

The point is signaled to turn right at the road junction. segeant n, commanding the machine-gun section, decides to egage the advance party.(2) Requirement.-The fire order.

'

<1ech;io



BASIC FIELD :MANUAL

(3) Solution.

Range 500.

No. I, road junction.

No.2, gate.

Scissors.

At my signal.

Commence firing.

1

117

(4) DiHcIl8Hion.-Fire is withheld until the advance party

in the opeIl, opposite the stone wall. The point is permitted

go by, as it is a less remunerative target than the advance

11h'ty. The moral and physical effects are increased by open-

~l;" fire with both guns simultaneously.b. Problem NQ. 2.

(1) Situation I.-An attack against the hill is held up by

aChine-gun fire from the small WOOds (target is 45 mils in

'1(llh). A machine-gun section has been brought up on a rise

I l'Pur of the friendly troops to neutralize the enemy fire. It

ll~ I)(>enraining and the ground is wet. Estimated range to

'Iendly troops 300; to woods, 800.(2) Rcquircment.-The tire order.



118 BASIC l"IELD :MANUAL

(3) Solution.

No.1,' range 800. or

Point where road disap-

pears.

Adjust.

Overhead.

Commence firing.

----------------------

All guns-850.


Edge of woods.

Scissors.

Overhead.

At my signal.

Commence firing.

No.1, range 800.

No. 2, 850.



Scissors.

Overhead.

At my signal.

Commence firing.

takes PO't

Sl~C01l0

FIG {iRE GO.-Problem No. 2

(4) Situation II.-The second section arrives find

sitlon on the left of the first.

(5) Requirem~nt.-The fire order;

(6). Solution.-l\!essage by runner to leader of thesection:

No.3, range 800.

No. 4,850.To your right front.



RASIC }'IELD MANUAL 119


Second section left.

Scissors.

Overhead.

At my signal.

Commence firing.

l\{(>ssage to leader first section: "Cover rigl1t of target."

(7) Di8CU88ioll.-Because of the wet ground the strike can

~ot UP seen; hmwver, it may be possible, at mid-range, to ad-

/ goo

~.l~~...FIGURE 51.-Pro1Jlem No. 3

"~

Il!iton the ruad, as the strike is likely to be Visible. If un-

lble to adjust, however, different range settings should be:l\>ento take care of a possible error in range estimation and

()insure hitting the edge of the woods. As soon as the cor-

eet range is determined all guns should be relaid with the

11'0{X'r sight setting.

o. Problem ]1;0. 3.

(1) Situathm.-A platoon on high ground supports the cross-

ng or a slllall creek. The crossing, is checked by fire, mostt Which seems to come from the two patches of woods. The

elllYcan not be s£'en, but each attempt to advance is met by.

"

~




Second section.

900.

To your left front.

Woods.

Scissors.

Overhead.

Friendly troops in small

At my signal.

Commence firing.

and

heavy fire. Range to left woods 900; to right woods

The right woods subtends 75 mils and the left woods 50 IT

(2) Rcquirement.-The fire order.

(3) Solution.

First section

1,200.

To your front.

Woods.

Inward traverse.

Overhead.

Friendly troops on far

bank of creek.

Safety limit: Line running

through road junction.

Commence firing.

(4) Di8cu8Bion.-Visible targets are not to be expected aga

an organized area. Leaders must engage the areas wllich S

to give the enemy the most cover and the best positions.

effectiveness of their fire must be judged br the actions of

enemy. In this situation the fire of the two sectiolls m

be crossed in order to obtain oblique fire.

d. PrOblem NO.4.

(1) Situation.-The battalion is held up by fire from

woods to the front. A section is working up the ravine to

left to flank the woods. The machine-f.,'1lllplatoon

the company has taken position on high ground. 'Woods

ure about 65 mils. The runge to the woods antI the ridge 1s

and to nearest troops 350 yards.

(2) Rcquircment.-The fire order.

(3) Solution.

Range 700.

To your front.Woods.

First section:

Front edge of wood,.

Inward traverse.

Second section:

Left edge of woods.

Fix.Overhead.

At my signal.

Commence firing.

er

1,

suppor m



i

BASIC FIELD :MAN VAL 121

(4) Discu8sion.-The parts of the woods from which the

emy may bring fire must be neutralized so as to further the

Vance. In this case, fire must be heavy on the front and

ft. Since the front of the woods subtends more than 50 mils,

ward traverse must be employed against this part of the tar-

(It. Fixed or searching fire may be used on the left edge of

e woods, as this portion of the woods will be enfiladed.

FIGL'ltE 1'i2.-rl'oblcm No.4

SI';CT10N XIII

IRECT LAYING ON LANDSCAPI~ TARGETS AT 1,000

INCHES

183. General.-Most phases of the technique of direct laying,

'ueh as fire distribution, overhead fire, target designation, fire

ontrol, and fire orders, may be taught on landscape targets.

The use of landscape targets makes possible the teaching of

direct laying indoors where conditions are unfavorable for

outdoor work. Instruction may be had with or without ball

allllllunition. 'Vhen ball ammunition is used it permits the

~'11Jlllerso see the results of their firing with a small expendi-

ture of ammunition. This tJ'pe of instruction should preet>de

direct-laying problems in the field, but should neyer replace

entirely actual field firing, except where lack of terrain pre-

cludes such firing.

989::;30-32--9



BASIC }'IELD MANUAL

184. Targets.-The targets used are the standard Series

landscape targets issued by the Ordnance Department.

targl'ts are SlIt up as shown in Figure 78. In order to eco

mize on the expl'nditure of tile recording panels, millleograpl

reproductions of seJectffi targets lllay be pr('pa1:('d and fasten

over the corresponding target on the upper panel beforefiring-.

185. Mounting guns.-The guns "are mounted on T

set flush with the top of the firing points. In order that fOl

guns may be fired on the sallle spt of targl'ts, the right Tshoul<1be 1;laee<1OPllosite the first or second panel from' t

firer's right. The T bases are placed so that the cross piecju,.:t touch each other.

186. Targeting.-The guns are targeted as for machine-g

marksmanship, as eXI)lained in paragrullh 83, using th(~ hIm

~o. 1 panel for this purpose.

187. Sight setting.-The guns, having bl'en targeted, mnow be aimed dirl'ctly at the targets on thl. upper panel wi

a sight setting of 441 ~'ards. For most direct-lasing problems

Is desirable to aim in this way, since the targets pictured in bla

and white ou'the recording panels appear, when vipwpd throu'

the maehine-gun sights, with the same Indistinctness charact

lstic of field targets. Occasionally' it may be desired to ha

the gunner' aim at the target on the eolor(-'dpa11('1with a sigsetting Which will cause the shot group to strike the correspon

lng point on the uPPl'r panel. 'Vhen the gun is pl.oper

mounted, this Right setting is 1,325, and shoulll be announc

prior to the delivery of the fire order.

188. Ranges.-It is necessary to use an assumetl range

com[llf>tethe fire tlrder. Small numbered cards, illtlicating hu

dred~ of ~'urtls of range, are tacked along the outer edgesone flank of the colored or recording panel. or both. (Fig.

The range then annqunced in the fire, order is merely for t9purpose of indicating to the gunners' ~'here to look for tile targe

189. Direction.-The <lirection is ann(mneetl as "Tofront," .. To )'our right front," and" To ~'our right flank," Int

eating the cpnter [lunel, the second from the right, and the

p'anel, resllectlvelr.190. Problems.-l\Iost direct-laying problem!'! should be fire

by spction, since the seetion is the fire unit, 'Yhich gives a lar

number of Rubordinate leaders experience with a smalltnrl' of ammunition.

T

ea

bas

ba

78.

yo

rigl

eXllen




91. Overhead fire.-Situations involv.ing overhead fire

IUlll be given frequentl~r. In order to use the overhead fire

~s on these targets the upper and lower panels mm;t be as-

eu to be one continuous piece of terrain; that is., the ground

tUred on the upper panels is assumed to be at a greater

1ge than that shown on the lower panels. The friendly

0lll'! are then placed near the lower edge of the colored

Ilels. The gunners first lay on the target with the announced

Itt !-letting llIHI, having cheeked safety, relay on the target

th u. setting of 441. .

192. Final protective lines and sectors of fire.-Landscape

~Ms are suitable for instruction in the preparation of data

dl"fensive fires. A sector of fire, defined by terrain features,

ltsjo;!gnedto a section of guns; one limit of the sector is

Illlllygiven as the direction of the final rJrotective line. Each

1111tleader is then required to prepare a range card so that

1llny fire, under any conditions of visibllit~r, along the final

ott'<'tiveline and on suitable targets within the sector. Each'

II Is laid in the direction of the final protective line with a

ht ~etting of 441 amI 11t a point 700 rurds from the gun as

(IWn by the runge indicators on the edge of the target. The

tll ore recorded and the gun is shifted to the other designated

I'g(lts and the data likewise recorded. The guns are now

Int('d UWllY from the targets, the targets covered with burlap

l'~('lIS, and the s(-'('tion is required to fire on the targets for

lth the data have been n'cordetl.

SECTION XIV

TESTS O~-.TRAINING IN DIRECT LAYING

93. Purpose.-Tests of training in direct laying will be held

the purpose of determining the proficiency of machine-gun

its In the technique of direct laying. They form the basis for

I1llatlng the quality of the technical training of a unit and

lll!-lha means of judging the ability of leaders to instruct

the Imh;ket.

94. Units required to fire.-Only those units which are

I IPI)(>dv1th mnchlne guns as a prindpnl weap<)ll are rpquired

nl]('r~o the tests which may consist of a series of problems

one or hoth s(>(.tions of the platoon. No unit larger than a

Itoon will be tested. •




195. When held.-The tests should be held after a co

of at least one week's instruction in direct laying following

reJnllar marksmanship season.

196. By whom conducted.-The tests will be conducted

an officer designated b~' the commanding officer of the reginlor separate battalion. \

197. Ranges.-Whenever practicable, the tests of train

should be held on ground with which troops undergoing the t

are unfamiliar. 'Vhere necessary the tests may oe held 0

landscape target set-up.198. Rules.-The officer ordering the tests of training

prescribe such rules as he deems appropriate to suit local COIl

tions. OtherWise, the tests will oe conducted. on thethe problems given in Section XII.

199. Procedure.-The tests will be fired under the direct

and supervision of the officer ordered to conduct the tests.

information other than time and place of reporting will bebefore the time set for the tests.

200. Results.-A careful record will be kept. The resl

will be transmitted to the officer ordering the tests in u writ

report. No. rating will be made. The officer conducting

tests may, however, mention defects or special pointsexcellence. --

order

gi



II

CHAPTER 4

1'ECHNIQUE OF MACHINE-GUN FIRE, INDIRECT LAYING

Paragraphs

lCCTION I. General 201-206

II. Theory of indirect laying 20i-208

III. Obtaining map data for a single gun 20D-210IV. Obtaining map data for guns grouped in battery --- 211-218

V. Obtaining data without a map for a single gun 219-223

VI. Obtaining data without a map for guns grouped inbattery 224-225

VII. I,aying and maintaining laying 226-228

VIII. Searching reverse slopes 22D-232.

IX. Defiladed firing positions 233-234

X. Training on landscape targets at I,OOO-inch and at

unknown short ranges 23~236XI. Tests of training in indirect laying 237-244

SECTION I

GENERAL

201. Definition.-Indirect la~'ing is the t~'pe of fire employed

Y nmchine guns when the target Is not visible to the gunner.

It involves pointing a piece for direction by directing the linelltablished by the sights upon a given aiming point, and adjust-

llg the weapon for elevation by means of a quadrant or eleva-

tIoll level.202. Uses.-By means of indirect laying effective fire may

e <lelivered by guns which would otherwise be silent. Indirect

aYlng is employed in the following cases:

u.• In the initial stages of the attack and defense by guns

t units in battalion, regimental, and brigade reserve.b. In firing from position defilade.

C. In defensive and withdrawal actions to place fire on roads,

rIdges, defiles, and fortIs until such time as the enemy presents

suitable target for direct laying.

d. When darkness, fog, or smoke obscures the target, machine

uus employed in the attack or defense must use indlrect-Iay-

ng methods even though these guns are primarily sited for

direct laying.

125




c. In some cases by a platoon of a machine-gun

f;upporting an assault company, when the other platoons

the machin ......un company have been displaced forward. .

203 .. Comparison of, indirect and direct laying-a. A

t."anfagcs.-Indirect laying increases the area available fa.

machine-gun positions. It is normally more difficult, due tless obs<>rvation,for the enemy to force g,uns sited for indir:~

laying out of action or into new positions. Indirect

permits the massing of more guns and the emlllo;yment of

of reserve units which would otlll'rwise he silent. Indirect

laying positions normally afford better protection to

and materiel, and als;) greatly simplify the problem of suppl1and control. .

b. Di-sadrantagcs.--close support in attack is difficult;

mally, Obscl'vation is lacking, and hence adjustment of

exceptional; ordinarily new targets can not he quickly

more ammnnition and tilDe are reqnired to engage any targetjo. Sum.ma.ry.-In general, Whenever a choice of methods i

open, fire by direct laying should be used instead oftng indirect laying.

204. Sources .of data.-Data for indirect laying may be

tained with a map or Without a map (ground-TOG

The former method is convenient and simple, but the

metbod has greater practical value in tbe field, alnce tbereoften a lack of accurate maps of large scale.

205. Requirements for proficiency.--a. A. high standard 0

profel'1sional effidl:'ncy is ne('essary to employ indirect

with accuracy and rapidity. The subject Is not difficult,

('lose attention to detail and practice In solving Indirect laying

problems are necess:iry to seeure proficiency.

b. A knowledge of map reading mm.;t he acquire(l prior to,jtaking up thi8 s'lbject. The correlative subjects; theory of fire

direct la~.ing, machine-gun illstl'Ulllel.,ts, and hattery drill must

he mastered in order to make progress in indirect laying.

206. Organizatiol1.-Indireet laying methods may be

plo~'ed by guns organizpd and controlled singly or in batteries.

Single guns Hnd batteries may t)(~further organIzed into

or more groups under a single command. As the simvlestof indIrect lasIng is by single guns this method will be takenup first In this chaph'r.

compnn1

laY1

gun

personne

nor

fir

engaged:

employ

ob'

lIIethod)

latt~t

"

laYin

but

em'

one

use



BASIC FIELD MANUAL

SECTION II

127

THEORY OF INDIRECT LAYING

207. Fundamentals.-Three fundamentals are to be con-ll<lered in indirect laying; direction, elevation, and clearance

If Inask or of 'friendly troops. Obtaining data for indirect

llYing resolves itself, therefore, into det<'rmining the data re-

11lhell to point the gun toward the target with the proper eleva-

:1011. 'When these data are correctly employed, the targ,et will

)~ 8truck, if no' intervening mask interferes. Hence the final

'eqUirPHlent is to determine whether the mask will be cleared.a. 7'hcory of dircction.-{l) Gencral.-Tlle theory of laying

gUn for direction h:r indirt'ct laying methods is based on the

!let that although the target may not be visible from the gun

IO~itlon, ~'et the direction (azimuth) of the target from mag-

l(itic north, or with reference' to some visible object, may be

letel'Inilled. Two general methods of laying for direction thus

Iresent themselves; laying by means of a magnetic azimuth,!l1d laying by Ineans of an initial aiming point (lAP) and'

!lse nng-Ie.

(2) La1ling by means of a magnctio azimuth.-The magnetic

Zhuuth (the flngle measured clockwise, between the magnetic

1(ll'itliull through the gun position and the line gun-target)

I determined, and the gUll is then directed on this azimuth

ing an aiming circle or compass, by methods described ineet!oll VII.

(3) Laying by means of an initial aiming point and ba8e

~'Yle.-An object such as a house or tree is selected as an ini-

nl aiming point. By methods to be described in Section III the

Il'ection of the target with reference to the initial aiming point

Idetermined; that is, it will be known that the target is a eel'-

ltn Angular distanc(j to the right or left of the. visible InitialInling point. 'l'he horizontal angle through which a gun turns

OnlIIn initial aiming point to a target, or hase line, is called

le !lllse angle. 'l'he gun Is laid on the initial aiming point

11(1 II'!turned through the base angle by means of the traversing

1,11 anll rear sight. (~""ig. l:i3.) The gun is then directed at

Ie ta rget or is In i<1on the bllse line.

b. I'll cory of elct'ation.-(l) Elevation fw range'.-When the1n II'! fired the hullet does not travel in a stralgilt line. It

!gins Its fUgllt along the line of departure (the prolongation

~




of the axis of the bore of the gun), then falls, under the actio

of gravity, describing a gradual curve. To hit a target

given distance away, the bore must, therefore, be elevated

tilted upward with reference to the line from ~un to targe(Fig. 54.)

- . :J 1AP--....,;--- B"$s, ANGLS.

GUN ~:::::: BA5~ .. £1

FIGGUE 53.-llase angle

(2) Angle of elevation.-The straight line connecting

origin with the target is called the line of site. The vertic

angle formed by the line of site and the axis of "the hore (liil

of elevation) when the gun is laid is called the angle of elev

tion (AE). The angle of elevation varies with the ran

t,"t O~ O~PAQTUll~

--- -- .............

'~AAGn

FIGGRE 54.-Llne of departure

Table I,"Fire-control Tables, Browning Machine Gun, gives t

angles of elevation for different ranges. Thus, to hit a targwhich is 1,500 ~'ards from the gun, it is necessary to elevll

the gun so tha t the bore forms an angle of 34.8 mils with t

line of site. (Fig. 5:5.)

t>OIl~

\1> o~1\lf,- ----- .................

-...."'"APlGL& O~ IOLE.VATIOM- \~4.8 "........ .........JLlKE. 011' aiTE.

1----------- l~OO YAA.OS -1

FIGGREl 55.-Angle of elevation

(3) Angle of quadrant clevation.-In laying a gun in ele

tlon when the target is not visible, some mechanical meamust be emplo:red. The piece may have to be pointe<1 slight

upward or downwar<1 with reference to the horizontal,

pt'nding on the location of .the target. (Fig. 56.) The ang

--------

~ ~ __ ~

t1

~

~



BASIC FIELD l\IANUAL129

tWhich the gun is laid is best measured from the horizontal,

,II the horizontal may always be established by the use of

e spirit level" on the clinometer, and the angles measured

IDward or downward from horizontal. Computation of eleYa.

FIGURE56.-Targets above and below horizontal

lion data therefore consists in determining the angle aboYe

~rbelow the horizontal at which the bore of the gun must be

laid to strike the target. Therefore the angle of quadrant el~

\'atlon is the angle between the axis of the bore (line of eleYa-

HOD)and the horizontal plane at the origin (QE). (Fig. 57.)

(4) Oomputing clevation.-There are three cases to be con.

si<lered in computing elevation, as follOWS:(a) When the gun and target are on the sa,me horizontaZ

TJlanc.-Assume the gun and target to be on the same level and

the range to be 1,800 yards. To hit the target, the gun must be

elevated at an angle of 53.4 mils above the line of site (53.4

lllils being the angle of elevation for a range of 1,800 yards).

'l'he line of site in this case is horizontal; hence the bore is

elevated at an angle of 53.4 mils above the horizontal. As the

QE is the angle which the axis of the bore makes with the

horizontal, the QE required to hit the target in this case is

[;3.4mils. (Fig. 58.)(b) When the target is a,bove the gUll.-Assume that the

target is higher than the gun and at a range of 1,800 yards.

(Fig. 50, CD.) It will be seen that if the gun were given a

QI~of 53.4 mils, the bullet would not hit the target, but would

strike the horizontal plane 1,800 ~'ards from the gun if it could




continue its flight. Therefore, to hit the target it is necessl1to give the gun additional elevation. This additional

{'quaIs the angle which the line of site makes with the 110

zontal (base of trajectory). (I~'ig.50, @.) This angle is call

--~-

~J4~.I •

f---- ----1800YAA08_ - - -- ----l}o'IGURE 58.-Gun end target 011 same horizontal plane

the angle of site. It is the angle between the line of sfte all

the base of the trajectory. From Figure-50 @ it is seen thl

the QE is composed of the angle of elevation and angle

site. The angle of elevation, therefore, gives sufficient elevatloto cause the bUllet to go 1.800 yards, and the angle of site give

1~.:>;1!--------1800 YAROS--- --- ---I(i)

•------1800YAnWI- -,

(!)

FIGURE uO.-Target above gun CD and (!)

the additional el(>vation required to. hit the target, because thetarget Is above the gun.

(c) When the target is below the gun (flg. GO) .-The angle

of site is negative when the target Is below the gun. In deter-

mining the QE, therefore, the angle of site is subtr,acted from

the angle of elevation. ItwUl be seen from Figure {)()that the.

QE equals the angle of elevation minus the angle of site.

elevati




(d) Genera,l rule for determini11{! QE.-In any case the QE

~qUalsthe algebraic sum of the angle of elevation and the angle

of site; that is, if the angle of site is positive, it is added to

the angle of elevation; if negative, it is subtracted. Angles ofelevation are always positive. If the angle of site is negative

11.1111 numerically greater than the angle of elevation, the result-

FIGURE GO.-Target below gun

ll.ntQE will be negative and the gun when laid will be pointed

helow th(~horizontal; if the angle of site is positive, or negative

hut numerically smaller thun the angle of elevation, the QE

\ViII,of course, be positive.

c. lIfaf.;k and troop dearance.-(1) Mask clea1'Ul1cc.-Before

f\r'ing over a mask, such as a hill or woods, it is necessary to

\{now definitely whether the bullets will dear the top of the

FIGl'REG1.-Angle of clearance

lIlask. This clenrnnce is best determined as is shown by the

fOllowing example: Assume that a target at a given range re-

qUired a QE of 73 mils (fig. (1), and that to hit the top of the

lIlask which is between the gun and the target would require

It Ql~)of 43 mils. If the gun were laid to hit the top of the

lIlask (with a QE of 43 mils), nnd then raised to 73 mils so as

to bit the target, It is nppnrent that when firing at the target

the mean trajectory will be going 30 mils (73-43=30) above

the mask. In other words, the angle of clearance (in this case

30 mils) is always the algebraic difference between the QE to .

the tllrget and the QE to t~1emask.



132BASIC FIELD :MANUAL

(2) Troop clearance.-It is also necessary to determine

whether it is safe to fire over the heads of friendly troops

The angle of clearance over the troovs is determined in

manner similar to that presCl'ibe<l for mask clearance.

(3) Required clearance.-Inasmuch as the bullets from

machine gun do not follow exactly the same path when fire

with a given direction and elevation, but form a cone of fir

similar to a stream from a hose, and as QEs to a target, mask

or troops are figured to place the center of the cone of fir

on the target, mask, or troops, allowance must be made to in'

~ure the entire cone clearing the mask or troovs. In addition,

in the case Where safety of troops is involved, the entire cone

must clear the heads of friendly troovs with a sufficient allo''''

ance for their safety even if some slight errors may have beef

made in laying the gun or calculating the data. The angle

of clearance required to fire over a. mask or over friendl1

troops at different ranges are given in Tables II and III, Fire-

control Tables. The angle of clearance above the mask ot

troops must equal or exceed the prescribed mask clearance, orthe safety angle, if troops are involved.

208. Basic data.-From the foregoing it is seen that the lol-.

lOWing information is required to compute data for indirectlaying:

a. The direction of the target from the gun with referenceto magnetic north or some known point used as initial aimingpoint.

b. The range and difference in elevation (vertical interval)between gun and target.

o. The range and vertical interval to the mask or troops.

SECTION III

OBTAINING MAP DATA FOR A SINGLE GUN

209. General.-The method of obtaining map data for a

single gun can best be illustrated by the solution of a concrete

problem. To facilitate the solution, a form of a work sheet,

shown in paragraph 210, is provided. The steps in the work

sheet and in the description of working methods are numbered

to correspond to each other. The two should be studied to-

gether. The arrangement of the detailed work should always

be adhered to. Neatness and proper arrangement will tend to




lb.inimize errors and will aid in the checking. of the work by

another officer, which should be done whenever practicable.

210. Typical problem.-a. Situation (fig. 62).-Fire-control

lb.llp,Fort Benning, Ga., 1:20,000; sheet 1. The situation is

as follows:

A gun is at (17.54-19.77).

The target is at junction of road anu trail at (17.2(3.-17.58).

The lonepine on Maxey Riuge at (17.04-19.04) will be used

as an initial aiming point.

Mask is Humphries Hill.

There are friendly troops on an east-west line at. (17.35-

18.26).

b. Requirement.-The firing data, to include the following:

(1) The QE (for laying in eleva tion ) .

(2) Tbe base angle and magnetic azimuth for laying in

direction.

(3) A statement as to whether or not the mask will be

Cleared.

(4) A statement as to whether or not it will be safe to fire

oVerthe friendly troops.




100 0 1 2. 3 4 5 6 ., 8 9 10ooyd3[H H H H H H

CONTOUR INTf.RVAL; 10~TFIGURE 62.-Plottlng single gun, map problem




WORK SHEET: SINGLE GUN, MAP PROBLEM

I'CGkuIation.s

Ma WxtoooR

2~.3111000

1.207

.. -lO.~

M' W x 1000"-.-Q --• +3.3i( 100Q...

10~3

+.3.0

At 2:300 -100.7AtZ2.oo'~

11•.5-a.ll-.l)05

90.0

4\.0

340

)-70-eo.3

(I) 1. Mar n. ~nmm~ J:,re Conl:ro1May Shui: No.1

(1-2.0,000) .2.@l\ at C17.5'!--l9 772'fargot at (17.2.(, hso)

(~)- Mash at HUo\PHBIU HILL

T..oop. at (17.35 llFZ.(,)

lAP o:t. Lon .. p,"$ 0-1: (17.0~ 19.04)

,'S. Dat.a from p1oHing,

a. Rang<!:~10.\ {Gun t.o Tartet 2207'''1__ Gun to M.cuK_-.:.l.::.o.::.6:.~_.-..-

<&u.no Troops _""15:.:Z:.:;)-------

b. t.lqvo'bonsuevat.on Ciu.n 410 ft

(4 ) ~~:~~t~~':s{"tE.Ievoi,on Iroop. -=~-,-7:.0-,-tt-,,--

4. '-Ievatlon Data (calcutated):

a. Gunto Igrtst.(5) VI, G ta 'T (YQrd5)-2~.3

IG) AS, G -to T -10.(,7) A.E., (i to r 90.0(8) Q.E., G to" 79.4

b. Gun 'to Mask

{

V!, G to .M.a.&1\ Cyorsls} +3 •.3(9) A~ G to 1'\0$11. +3.0

Ak.J <& to !'\a&K 17.7-Q£, G to }1~ ZO.2

(10) .Angle of clearance :>9. z.

f

J 2eQd c:ltara.t1ce 7.Z(II) Mll!k will .(wHi-ftOf) be deal'ed;

Clearance over

I'e~.a+52.0

c. Gun to 1r$!ops

{

VIJ (z'{o troops Cyard$) -t~.S

AS, G to iYoop$ 7(Iz.) -_ AE.. Ci to '1't'OOP$ oS .t

Q'-. e;,+.oYroop. Z7.4 ~9.4-(I~) Antle of cICQI'QTl« SZ.o 274-

RC'l'd safety an Ie 41.;:' --'-

04) --{iI'OOP''''ilI (~)bc _ofo) 5Z.0CleQranc4 ever !'<t'l.'J ~A ..:!::..!2..:.L

5. Diredion Data(1:1)_<:'r'o aZimuth. G to 1 ~~29(16) -.Magnd:ic a:.<mu-l:h, Go to 'J' ~>"(11) -Clc:ue (\"~le . R 4-90

Af. 1600. 40.4-At.1500.~

.s...

-idt"... \..safrij'AnjIClIboo ..

1500 • 40.3

40.3 4"2l.

G. Firms "Daola -'-~-

flAP Lone p,M at (11.04-1' 0;4:) 41.3 A~r.

06)- P.>Q5e angloz R490 .fI'tognct,(', Qr;lmu{h.~33~1~G~

19 1='1uNd Qt to neot'e.st. mil

C. Preliminary steps (see work sheet above).-Step i.-Note

the title and l';eale of the map.Step 2.-Locate gun, target, mask, troOl)S, and initial aiming

lJoint on the map, giving locations by coordinates or by de-

Scription. To mark such points on the map, a pin or similarly

=

-

~

~ -

-

-

__

~ -- -=~~~~~~~~~---

_

__ ---- __

__ __

'

- ~ --

~

~

~~ _

~~ __




sharp-pointed instrument may be used. A circle may be dra",l1

around the pin point with a pencil to facilitate finding it.

Step S.-Using the map scale, or the sca'e on the protractor,

measure the ranges, gun to target, gun to mask, and gun totroops. These are found to be 2,207 ~'ards, 1,083 yards, and

1,523 ~'ards, respectively.

Step 4.-Determine the contour elevations of the gun, target,

mask, and troops. The gun position on the map is exactU

on the 41Q-foot contour, and its elevation is therefore 410 feet.

Similarl~', the elevation of the target is found to be 340 feet,

that of the mask 420 feet, and the troop elevation 370 feet.

Elevations of points lying between contour lines are found

by interpolating between the proper contour elevations.

Step 5.-Determine the vertical interval gun-target by sub'

tracting one elevation from the other. The difference in ele'

vation or vertical interval gun-target is 410-3tO or 70 feet;

that is, the target is 70 feet lower than the gun. This

tance must be reduced to yards and equals minus 23.3 yardS;

minus, because the target Is below the gun.

Step 6.-Calculate the angle of site. It being determinetl

that the range gun-target is 2,207 ~'ards and that the target

Is 23.3 yards below the gun, the angle of site may be cal'

culated by the mil formula:

}[="TV X 1,000.R,

Substituting the values for "TV (width or height) and R (range),

J l (the angle of site) Is determined as follows:

,M -23.3 X1.000 10.62,207

pIlnus because the target is below the gun.)

Step 7.-Determine the angle of f'levation. If the gun wer

laid at an elevation of 10.6 mils below the horizontal, the axi.of the bore would be pointed at the. target, provided the gull

has previously been laid for direction. However, since tbe

range to the target is 2,207 yards, the gun must be elevated

through an additional angle sufficient to cause the bullet to

carry that far. Angles of elevation for ranges of hnndrf'ds 0

yards are shown in Table I, Fire~control Tablf's. The angle

of elevation for 2,300 yards is 100.7 mils and that for 2,200

yards is 8!).2. Interpolating: between 2,200 and 2,300 (see in'

structlons given with the table), the angle of elevation for

2,207 is fo.nd to be 00 mils.

<1i

-




~tep B.-Determine the angle of quadrant elevation. From

at has already been computed it is seen that, to hit the tar-

:t, the gun would have to be elevated -10.6 mils for angle

site and 90 mils for range. lienee the QE equals the alge-alc sum of the angle of site and the angle of elevation

"10.6+90) or 79.4.

~OTE.-The QE for any range and the vertical interval (VI) may beU!npddirect from Tables IVa and IVb, Fire-control Tables, without

: neceflsity of computing the angle of site. Instructions are given

h the table. Either mf'tho(}may be used. The tables wlII save time

thoRefamiliar with their use, but the method described above should

stUdied in order that the fundamentals of indirect laying may berOugblyunderstooJ.

~.Mask clearance.- (1) GC'fICral oo'nsiderations.-In indirect

~lngthere is generally a solid obstruction such as a hill or

IOds between the gun and the target. The map must be in-

cted to determine the location of this mask. The highest

~rvening crest is generally the mask, though sometimes it

ly be a lower obstruction near the gun or target. If thereany doubt as to which obstruction is most likely to mask

fire, clearance is figured for all such obstructions. Trees,

Cial1y thick woods, must be considered, and their height

ded to the height of the mask. Fire may be delivered

rOugh a thin fringe of trees, if there are no friendly troops

'ated near their fill' edge. Thick woods will stop or defiect

~t of the shots and render the fire ineffective. 'Voods areIlally shown on maps, but, if not, reconnaissance will deter-

!leWhether they must be considered. In this particular case-

inspection of the map shows that the point most likely to

:erfer(~with the fire is Humphreys II ill. A line is drawn

11ll the gun to target, and the highest elevation cut by this

e as It crosses Humphreys Hill locates the mask.

~tep 9.-Determine QE to mask. When obtaining data from!lap, the best means of determining mask clearance is to com-

te tile QE to hit the top of the mask, and then see if the

to tile target, which has already been figured, exceeds the

to the mllslt by the required amount. The QE to the mask

determined by the same methods as were described for QE

turf.\:et. In this case the QE to hit the mask is found to

20.2.

~2)Gomputinq maJ;k vlearance.-The mask clearance is com-

:(\dhy the following stpps:

ORfl53°-32--10

~

~

'



138 BASIC FIELD l.IANUAL

Step 10.-Subtract the QE to the mask (20.2) from the

to the target (79.4); the difference is the angle of c1earll(fJ D.2).

Step 11.-Required clearance. To determine that this cleance is suffici(>nt to allow the entire cone of fire to clear

mask, the requir(>d mask clearance for a range of 1,083 yll(the range to mask) is obtained from ~rable III,

Tables. The required clearance for 1,083 yards is 7.2

'1'he angle of clearance is 5D.2 mils; and since only 7.2

clearance is required, the mask will be cleared by 52 mils 0

the required clearance. (E'ig. G3.)

e. Troop salety.-Safety for overhead fire is detenui1

in the same manner as mask clearance. The position or P

tions occupied by friendl~' troops in the line. of fire

been plotted, it may be neeessary to determine troop safety

eaeh position. 1I0w(>ver, an experienced offieer will usuallY

TOTAL CL£ARANC£

5SoZI11LS

R£Q(/IR£.DCLEARANCe.

7.2, MILS

FIGCRE 63.-Clcarance over required

able to select the position whieh is most likely to be endange

and thus determine snfety by a single calculation. FolIo'"

are the steps required in this computation:

Step 12.-In this ca!o;Che friendly troops are on an eastA

line at (17.35-18.26). The QE to the troops is found in

same manner as described for finding the QE to the target.

The QE to the troops is found to be

Step 13.QJ;J to targeL 1,

QJ;J to troops_____________________________________

Angle of clearance_______________________________ D

Step 14.-The required safety angle for troops at a range

1,523 yards (the range to the troops) obtained from Table

Fire-control Tables, is found to be41.3

mils. The angle!

clearance, 52.0 mils, exceeds this angle. Itis therefore safe

fire. (Fig. 64.)

f. Obtaining directi{)n data.-Mask and troop clearflJl

should always be ehecked before determining direction (1:1

I!-'ire-co

II

h8,,

~




I

'lluflicient clearance <loesnot exist, this will obviate the neces-

ty of figuring the latter <lata. There are two general methods

laying the gun for <lirection, as outlined in paragraph 207a.

e first requires the magnetic azimuth, gun to target. This

:1ll1uthmust always be determined no matter which method

Used so as to insure accurate laying under any condition of

lbility. The second method requires an lAP and base angle.

~elllagnetic. azimuth can not be determined directly from the

aI>. The grid azimuth (the angle measure<l cloekwise from

Id north to the line gun-target) is measured with a protrac-

~. This is converted to magnetic azimuth by using the declina-

)n Constant of the instrument which is to be used in laying

gun. If the declination constant of the instrument is not

laWn,then the grid azimuth is converted to magnetic azimuth

applying the magnetic dC'clination shown on the map, cor-

TroofoS

1.'IGUHE

G4.-Clearance over required safety angle

ted for the mean ,annual declination change. In this problem

I datu for both of the general methods are shown as follows:

~tep 15-Grid Gzimuth..-To determine the grid azimuth,

Ilong the line gun-target until it intersects a north-south

d 01' draw a line pnrallel to the north-south grid which

!rsects the line gun-target. 'Vith a protractor, centered OIl

! intersection, read the angle clockwise from grid north to

,line gun-target. In this case the grid azimuth is 3,329 mils.

rtcp 16-:Magnctio azirnuth.-li'or Fort Denning, Georgia, the

-netlc declination correcte<l for annual change 1929 is ap-

I)(imutely 13 mils east. This <leclination of 13 mils must

l'efore be subtracted from the gri<l azimuth, which gives a

gnet1c azimuth of 3,316 mils.

'tep 17-B(JA8e a,Jlgle from IAP.-Draw a line from the gun

lUgh the lAP. With a protractor measure the angle be-

'en this line and the line gun-target; this is the base angle,

angle through which the gun must turn froUl the lAP in

~

~



BASIC FIELD MANUAL

order to be laid on the target. In this problem it is,

~m~ .

g. Step 18-Firre da.t(ll ....:-The data required to lay the gun

direction and elevation are noted. With the magnetic

or base angle from the lAP, and the QE, the gun is laid to

the target as described in Section VII.

SECTION IV

OBTAINING MAP DATA FOR GUNS GROUPED IN

BATTERY

211. General.--:-The method of computing data for a batte!

can be illustrated best by the solution of a concrete

The problem selected for solution involves a b~ttery of

guns engaging respectively an oblique, an enfilade, and a poi

target. The principles shown apply to any number of

grouped in battery. All calculations made in filling out t

battery chart should be carried out to include the first

place, and so entered in the body of the chart. The

in the fire orders, how~ver, are made in the nearest

mils. Refer to Figure 65 for a diagrammatic explanation

battery angles.

212. Situation. Fire-control map, Fort Benning, o

~: 20,000; sheet 1. The situation is as follows (fig. 66):Base gun: No~1 at (16.44-18.12).

Battery front: 100 yards extending northwest.

Initial aiming point: Lone pine on Maxey Ridge at (17.

~9.04).

Target A: At (18.54-18.97)-(18.48-19.18).

Mask: At (17.87-:..18.70)(allow 80 feet for trees).

Target B: At (18.46-19.42)-(18.70-19.60).

'Troops: At northwest-southeast line through (17.85-19.00

"l'atget C: (18.03-19.40).

Base lines on target A; (Base lines will be located onmost important target or in. the most convenient directioO

213. Requirement.-Completion of the battery chart shO?

in illustration. (Numbers in parenthesis refer to step numb

e

in the text.) .

214. Proce~ut:e.-Step l.-Plot the battery position on

map by locatmg the base gun (usually, as in this case,

No. 1 gun) and drawing the battery front to scale, in

designated direction. .

140

Rig

' aZimu

proble

fo

gu

deciII

entri

wh

-

J

'



5 Base stakes out.

(37)

L8

L16

R580

R500

2

4

FIRE ORDERS

- No.4 Time0.3 Trav-Search Rateo!- erse

QE per gunup flre

From ToE - ------ --- --- ---107 109 36 20 125

- --- --- --- --.1591~

12 20 125

---

"I~__6 16_ ._

--

- Task C Task DaskB

L;;'on base lines Lay on bas e l ines Lay on base l ines

Sight Dial Sight Dial Sight---- R9 L300 R5LiSO-- ---L160 R15 £280 . R9

---- --- --_.L160 RI £260 RlS

--- ---'-LUo R7 £240 R17

- Green Yellow

-

--~8953-32 (Face p.140.)

BATTERY COMMANDER'S FIRING SHEET

Date, 1 APT 30 T'

~a~Jery: A, Group i1Je 6Unir is t P lu t. , Co. D , 29th In /.r~ az~muth I. A. P'6 Deel grid to magnetic, E 13..

Gnd aZimuth base l ine, ~~2I0. Magne tic azimuth base l ine, 1 ,197 .

PREUMINARY ORDER

Dial Sight

R600 L12

(34)

Lo ne pine a t

1 lit.P. (17.04-19.04)2 guns on I. A. p3 No.1 gun base gun:

rn i

Task Wind- ~I No. 2 / Nage

QEQE--A- ...;...--

_~1105_

B_ 123 i 141

__C_I=r---;-i. , ,-D crr:cREMARKS

NOTE.-Numb' : . fer to step numbers in text.er s In ParentheSIS re

REMARKS

Prepared by A. S. N ..

Checked by R. B. R .

BA' I'TEfRY CHART

89.7

187.9

Batte ry angle ofparal lax 96.

Dis tr ibut ion d iffe rence (12) for paral le l f ire,

32.

Grid azimuth I. A. P ., (8) 598.

Gr id az imuth base l ine s, (9) 1210.

Magne tic azimuth base l ines (10) 1197.

Base angle -right ( le ft), (11)612.

89.8

117.3

169.21.2

15.3

90.0

GUN ELEVATIONS

TASK ORDERS

(35) (36)

Tas~Target ~~~:- Search Rate of -No. ----L

Angle of Bat angle f t per fi T a- b---shift D or C ron

l) per gun re Y on ase lines

(mi s gun

Dial

(13) 0 (14) DL58 (15) 100 ---;:; (16) 20 --- ;; ; 1

_------ 2 RI9

+20.0 (21) L189 (22) CR42 0 (23 )12 (24) 20 125 -3- --;;;;-..:..- RI8

---- ---28)L305 (29) CR48 0 (30) 16 (31) 16 125 _4_ L40 R1B

_---------- Stak~

(7) +44.29.9

ClearanceVI QE ov~r

troops troops reqUIredor ma sk or mask m:~~ l; :r -

safety angle

Mask or troops:

A Mask , t re es a t ( 17 .87-18 .70) .

C

B Troo ps on NW-SE . line throu gh (17 .85-19.00).

D

(6) 1,567 +33.3

Range,troops,or mask

(20 ) 1,675 +33.3

90.289.7

133.0187.3

VI tar- QE tar-get

(yards) get

GUN ANGLES FROM BASE LINE

(4) 2, 283 +32. 7(5) 2, 327 +35.3

Rangetarget(yards)

(19) 2,4 20 +40.32,750 +41.3

(27) 2,067 +30. 02, on +28.7

A

B

c

D

Task

Battery A, Group III. Composition, 1st p la t. , Co. D , 29th Inf ., No. of Guns 4.Base gun No.1. Battery front 100 yards. Commanded by Lt. R. B. Jones.Extending NW. Place, For t Benning , Ga.Location of base gun (16.44-18.12).I. A . P. Lone pine at (17.04-19.04).Location ofbase l ine on Tusk A.Map FOTtBenning, F. C.1;1J0,OOOheet No.1.

Task:

A (18.54-18.97)-(18.48-19.18)

C (18.03-19.40)

B (18.46-19.4.2')-(18.70-19.60)

D

Dif. DorC 1 2 3 4 Dif.QE+ I 1or

--_.A (17) DL19 0 L19 L38 L58 (18) +2.0 113.3 1

B (25) CR14 L189 L175 L161 Ll1,.7 (26) +18.2 133.0 1

---' --.

c I (32) CRl6 L30/j L289 L273 L257 (33)-.2 90.2

--I

I

---. ._-_.I. I

D!I

_

"

---

---

____ ~ __ ---

~

---

-- -

- --

---

-- __

~ ~ ~ ----------

___ ________

~

-




UGt.ND

Q botte~ o':"J feof paralIQXb e>ase anql.e

C flQH~ ansl« of dlstrlbutloR

d ArtlJle of .slilft.

eatu':j Qn~rt; of co~encto!eos~ Gun

FIGURE 6ri.-Battery angles

tio4

Step 2.-Locate targets, initial aiming point, an~ troops or

task on map .

.215. Solution of Task A.-a. Step 3-Plotting.-Draw lines

'om hoth flanks of the ha ttery to the initial aiming "point andI the targets. The line from the base gun to the right of'

Ie principal target is called the base line of the battery. The

ase lines of the other guns are parallel to the base line of

Ie battery.

b. Quadrant elevations.-When the range and elevations of

ilJ .k guns are different, it is necessary to figure QE separately

r each of the flank guns of the battery. This is done as

lIo\Vs:

Estel) .~.-For No.1 gun (to its part of Task A) :nange 2, 283

Ell~vation "0 320

El evat i on T_______________________________________ 418

"\71- ... Plus 98 feet equals plus 32.7 yards.AS Plus 14.6

AE 08.7

QE 113. 3

~

~




Step 5.-QE for No.4 gun (to its part of Task A) :Ek~nge____________________________________________ 321

oio', 3Z~

Elevation G _Elevation T______________________________________ 4'VL Pluf3 10.:; fept f'quals plus 33.3 yal'd~AS __~________________________________________~us 1~

AE 104. I

QE 11

fB

.scale: 120000

tO j ENtEA'~d U H j4rO Jctrr18

Contour Interval 10ft..FIGURE GG.-Plottlng battery map problem

c. Mask.-The mask is the edge of the woods. As No.1 gl

has the lower QE, the mask clearance is determined for

alone. (In some cases it might be neeessary to cornpute mll

clearance for both flank guns, to be sure all pieces would cle

the mask.)

Step G.-For No. 1 gun-Range to mask 1,5

Elevation G______________________________________ 3

Elevation m!lsk 300, plus 30 f('et for trees equal 420 fe

VL Pluf3 100 feet, or pTus 33.3 yu!'

AS Plus 21

~

~- - - - - - - - - - - - - - - - - - - - - - -

__



I

I

f


Step G.-For No.1 gun-Continued.AI ~ 38. 6

( ~E 5~9

Step 7.-1\1ask' elellrancl:'.QI!J to T ,,;. 113.3

QI<J to mask_______________________________________ 59.9

Clearnuce 53.4

'l.'he required clearance is 9.2, from Table III, Fire-control

'l.'ables. The elearance over that required is plus 44.2, and the

Illttsk

does not interfere with firing.NOTre.-IIaving determinpd that the mask will be cleared, the next

~tep 18 to determine direction data.

d. Step 8-Grid azimuth of initial aiming point.-With a

Dl'otrllctormeasure the grid azimuth of the line from the base

~Un to the initial aiming point. Itwill be found to be 598 mils.

i e. Step 9-Grid azimuth of base lines.-With a protractor

Illf>-Qsureile grid azimuth of the line from the base gun to its

nank of Task A. It will be found to be 1.210 mils.f. Step 10-Ma!lnetio azimuth of base lines.-(l) Convert

the grId azimuth of the base line to magnetic azimuth by cor-

l.'etillgfor thp. declination of the magnetic needle from grid

~Orth for the particular locality (13 mils east for Fort Ben-

Illng) : 1,210-13=1,197.

l (2) If the declination constant of the instrument to be used

to lay the battery is known, that figure, instead of the declina-

tion shown on the map, will be used to convert the grid azimuth

1° 1llag-lleticf1zimuth.

! NOTFJ.-Refer to Part Two, Chapter 1, Section I, for n dIscussion of

l~e Il1l'thod of obtaIning the declination constant of an aiming circle

~nd an explanation of its use.

fl. Step l1-Base angle.-With the protractor measure the

ll~leformed by the line from the base gun to the initial aiming

)lnt nnd the base line of the battery. It will be found to betght (i12 mils.

h. Step 12-Battery angle of parallam.-Measure the angle

rlned by tl}(~ lines connecting the flanks of the battery and

b lAP with a protractor. It will be found to be 96 mils.~h'ide by the number of guns to be turned away from the base

llill(in this case 3) to get the distribution difference for parallel

~e-{)Hdivided by 3 equals 32.

~

~




i. Step 13-AngTe of 8hift.-Base lines are on Task A in tl1

problem; therefore the angle of shift is zero.

j. Step 14-Batterll angle of di8tribution.-When the widththe target is such that parallel fire will not exactly cover it, t

fire must be distributed so as to cover all parts equally.

the angle through which the gun on the flank away from tl

base gun is turned to lay on its flank of the target is measure

then the angle which the other guns will have to turn may

computed. This angle is determined as follows:

(1) Draw a line from l'o. 4 gun parallel to the line frol'o. 1 gun (base gun) to its flank of the target.

(2) Measure the angle between this line and the line co

necting l'o. 4 gun with its flank of the target.' This is t

battery angle of distribution. In this case it is Left 58.

k. Step 15-Traver8e (when ta.rfJethas width).-(1) DraW

line from No.1 gun to the left flank of the target. With

protractor measure the angle between this line and the IIconnecting l'o. 1 gun and the right flank of the target. Tb

angle, the battery front in mils, will be found to be 100 mi

(2) Divide by the number of gun intervals (in this case

to find the traverse per gun-1oo divided by 3 equals 33.3.

the fire order use 32 or 36, so that the traverse per gun

be divisible by 4.

l. Step lG-Sea,rcking.-In order to compensate for IIIerrors, errors in figuring data and applying them to the gu

and to insure overlap of beaten zones on enfilade targets, so

search is always ordered. This search is applied to each gt

The proper amount of search to order depends on the type

target, the range to the target, the slope of the ground at t

target, and the accuracy of the data. In other words, t

amount of search is a matter of judgment on the part of t

officer figuring the data. However, as a guide, for targ

located on level ground a search equal to 20 per cent of t

angle of elevation of the base gun but not to exceed 20 II

should be ordered. This amount of search is approxlmat

correct for normal indirect-laying ranges based on the followl

assumpUons: I!""irst,that a runge error of 10 per cent should

provided for, and second, that a battery of four guns can

cover effectively an area of greater depth than 200 yards.

this case 20 per cent of the angle of elevation (V8.7 mils)

'"



i

r


the base gun is 19.7 mils; hence the amount of search to be

Ol'der(ldis 20 mils, as the search should be divisible by 2.

m. Step ["I-Gun angles from base lines.-By dividing the

battery angle of distribution (see j above) by the number ofgUnswhich. turn from the base gun, the gun angle of distribu-

tionis obtained. In order to place each gun on its proper part

Of the target, No.2 gun turns through this angle from the base

Un; No.3 gun turns twice this angle; and No.4 gun three

hues this angle. In this case, the gun angle of distribution is

19 (58 divided by 3), and the direction is left. Hence, No. 1

eingthe base gun and the angle of shift being zero, the anglesor the guns are as follows:

~o. 1, O.

I ~o. 2, left 19 from its base line.

.~o. 3, left 38 from its base line.

, ~o. 4, left 58 from its base line.

n. Step 1S-Gun ele-vatiol1s.-(1) \Vhen the flank guns have

~itrerentQEs, it is necessary to distribute the difference be-

t\\'eenintermediate guns, as follows: .i ' Qli.:for No. 1 equals 113.3

l QE for No.4 equals 119.4

i Difference 6. 1r (2) Divide by number of gun intervals--G.1 divided by 3

;qUals2.0; this quotient is added (since the QE of No.4 gun:~the larger) successivelr to the QE of each gun, as follows:QI~ No.1 gun 113.3

Q~J No.2 gun 115.3

r QI~ No.3 gun ..,. 117.3

, I QI~JNo. 4 gun '- 119.4

, 216. Solution of Task B.-a. Quadrant eleratio1ts.-This is

In entllade target. Lines have been drawn from No. i and No.guns to their flanks of the target. The QE for each flank

~n is computed separately as in paragraph 215.

Step 19-I QE for No.1 equnls -' 133.0

l QE for No.4 equnls 187.3

Ib. Pt'icndlll troops.-Troops are on a northwest and southeast

~e through (17.85-19'{)O). As No.1 gun has the lower QE,

e cll'urance is figurt>d for it alone, as follows:

~

----------------------------------

~

~



I


Step 20.-Range to troops 1, 675

Elevation G______________________________________ 320

Elevation troops__________________________________ 420VL Plus 33.3 yard9

-------491E to troops_____________________________________ 6.QE to T equals .. 133.0

--->ifference___________________________________ 68.1

Required safety angle_____________________________ 48.1

(Table 11, F. C. T.)Clearance over required safety angle Plus 20.0

c. Step U-.4ng7e of shift.-With the protrnctor measure tIle

angle through which the base gun must turn from its base

line to engage its part of Task B; this angle is Left 189.Q

d. Step 2.2-Battery angle of cOftverg(Jtlce.-In this case tlJe

guns must be clos~d from their parallel lines toward the base

gun in order to be on their proper parts of the target. To de'termine the angle procee(l as follows:

(1) I>raw a line from No. 4 gup. parallel to the line, baSe

gun-its flank of the target.

(2) Measure the angle thus formed which is 42 mils. Havi!lg

determined this angle, the angle through which each gun ml1~t

close toward the base gun can be computed.h

e. Step 23-Traverse.-I!'or targets \vhich theoretically do not

require traverse, such as enfilade or point targ,ets, it is, never'

theless, actually neeessary to traverse in order to allow tot

possible errors in obtaining and applying direction datS,

Therefore, a traverse of 8, 12, or 16 mils, depending on tlJe

accuracy of the data, will always be ordered on such target~'

In this case 12 mils would be satisfactory.

f. Step 24-Search.-In this case the angle of elevation tot

base gun equals 116.4 mils. ApplyIng the rule given undet t

Step 16, it is found that the search to be ordered in this case

is 20 mils.g. Gun angles from ba8e line.-To engage Task n, all gUJl5

must move through the angle of shift (Left 189') from theit

base lines. ThIs will l,lace the base gun on its proper part of

the target. However, the remnining guns must he convergc11

1~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I




~o\Vardthe base gun in order to be on their proper part of

lhetarget. These two operations are combined in figuring the

~Un angles from base lines as follows: The battery angle of

~Onvergenceis Hight 42 mils. The gun angle of convergence

'S found by dividing this amount by the number of guns which

Urn toward the base gun (42 divided by 3 equals 14). Since

:he convergence is in the opposite direction to the shift the

tun angles from base lines are-

Step 25.-No. '1, Left 189.

NO.2, Left 189 minus Hight 14 equals Left 175.

. NO.3, Left 189 minus Hight 28 equals. Left 161.NO.4, Left 189 minus Hight 42 equals Left 147.

h. Step 26-01ln elevations.-The "differ<.>ncen QEs is dis-

l'ibuted as for Task A. (Step 18.)

217. Solution of Task C.-a. Step 2i-Q1Iadrant ele'fa-

lans.-Lines have been drawn from the No.1 and No.4 guns

o the target. QEs for the flank guns are computed separately

lEI in paragraph 215. TIle Qgs are found to be: No. 1 gun,0.2,No.4 gun, 89.7.

b. St(~P 28-Angle of shift.-'Vith the protractor measure

he angle (Left 305) which the base gun must turn from its

'aSe line to engage its part of Task C.

c. Strp 29-Batterll angle of eonvcrgcnce.-In this case, the

Inesof fire must be closed from their parallel lines toward the

'ase gun. The battery angle of convergence is obtained as fol-)\Vs: 'Vith protractor measure the angle formed at the target

the lines drawn from the flank guns to the target; it will

e found to be Right 48 mils.

d. Step 30-Travcrse.-A traverse of 8, 12, or 16 mils may

ordered. (Step 23.) Assuming the exact location of Task C

ifJicult to determine, a traverse of 16 mils is ordered in this

Qse.

e. Step 31-Seareh.-A search of 16 mils is ordered. (Stepa.)r. Step 32-0un angles. from base lines.~The gun angles

~Olll hllse lines, determined flS in U above, are as follows:

No.1, Left 305.

No; 2, Left 305 minus Right 16 equals Left 289.

No.3, Left 3m minus Hight 32 equals Left 273.

No.4, Left 30;:)minus Hight 48 equals Left 2;:)7.

l

~

~

"




g. Step 33-Gun elevation.'l.-Some point targets may require

different. QEs for the different guns. In such case the QIDot

each fiank gun is calculated and those of the interiorfound as before. In this case each gun has approximately tbe

same QE, DO mils. Exact figured QEs are found as in Step 18,

218. Orders.-The body of the chart having been completed,

the data contained therein are used to complete the orders illthe battery commander's firing sheet. These orders are used

in making out the gun charts (s(~ebelow) by the .battery cow'

mander when he issues the fire orders to the Hattery as a whole.These orders are filled in as shown on the battery commander'Sfiring sheet, battery chart. .

GUN CHARTGrid azimuth of base line, l,ttO.Magnetic azimuth of base line, 1,197.

Gun No.~'Battery l'

Date, 1 Apr., 9

TimeTask

From To D!al Sight Norm AdJ

~~~:. Search Rate Color of

per up per of fire stakeSgun gun

---- ---- -- ------- --- --- ------'

16 16 1$15 Ye[{otl)

-------_ ....

R 13 82260

A______ L to R 18 107 36 20 125 Red

---- --.----------'B______ L 160 R 1 159 1$ 20 125 Green

------ --------- ....

--------REMARKS:

Step 34-Preliminar1l order8.-Lines 1, 2, 3, and 5 are self'

explanatory. Line 4 is filled in by entering, in terms of dial

and sight, the an~les necessary for each gun to turn in order

to lay on their respective base lines.

Step 35.-4. Task orders (Task A).-The angle of shift

and the gun angles of distribution or convergence are coDl'

bined into one command and placed ovposite each gun in termS

of dial and sight. Since the angle of shift for Task A is zero

(Step 13), only the gun angles of distribution are considered.

(Step 11.)b. Fire orders (Task A) .-To vrevent gunners searching be'

low the safety limit when firing over the heads of friendlS

troops, gunners are trained in battery drill to search onlS

upward from the QE ordered. Whether the initial bursts will

be fired with fi:;ured QEs nnd the search applied in both direc'

gUll

"

'

-------

-- _




tions, or fired with minimum QEs with all search Up is a

matter of judgment on the part of the officer in charge of the

:firing. If the' mission is merely to cover an area which will

include the target, all search will be Up, as the manipulationis more simple, and there is less danger of searching below

the safety limit. If the nature of the target is such that it

appears essential to place the initial bursts, if possible, 011 the

target, then the figured QEs should be uSfd, search applied in

both directions, and depression stops placed to prevent reduc-

tion of QEs below the safety limit. In this case, the fire order

is bnsed on the assumption that all' search should be Up.lIence the QEs announced in the fire order are less than the

computed QEs shown under" Gun, elevations" by an amount

equal to one-half of the ordered search. Example: The com-

Puted QE of the hase gun (Step 18) is 113.3; this is reduced

by 10 mils (Step 16), giving 103.3. The QE ordered is 103

since QI1Jsare always taken to the nearest mil. Where the

troop clearance is not sufficient to permit the reduction of theQE by one-half the amount of search, the QE is reduced by

the amount of troop clearance, and a search Up equal to the

sum ot the troop clearance and half the figured search is

ordered. Example: I1'igured QI<J60, troop clearance 4, search

per gun 12. The QE announced in the fire order would be

60-4 or 56. The search announced in t'he fire order \vould

be 4-t:6 (one-half of 12), or 10.

NOTID.-Reduction of computed QEs must not exceed the clearance

over required safety angle. (Step 20.) The traverse and search are

filled In by reference to Steps 15 and 16, respectively.

Sleps 36 anit 37.-0rders for Tusks Band C are filled out

in a similar mfl;nner.

SECTION V

OBTAINING DATA 'VITIIOUT A MAP FOR A SINGLE GUN

219. General.-When no suitable map for use in obtaining

indirect laying data is available, data are obtained by instru-

ments from a ground reconnaissance. These ground methods

have been named TOG methods, since they involve the three

points T (target), 0 (observation point), and G (gun).

Wherever practicable, a single or, from which both gun and

target can be seen, should be selecteJ.; where this is not pos-

Sible, it will be necessary to use two or more OPs.

220. TOG, single OP method; procedure.-a. The method

of obtaining data for a single gun by means of TOG, single or




method, can best be illustrateo. by the solution of a concrete

problem. To facilitate the solution a form of a work sheet as

shown in paragraph 221 is provio.ed. The numbers in paren-thesis on the margin of the work sheet correspond to the num-

bers of the steps in the following description of workingmethods.

b. Obta,ining prelimina,ry data 1dth in8truments.-'With an

aiming circle measure the magnetic azimuths ano. the angles of

site from the OP to the target and to the gun. 'With a range

FIGURE 67.-0btaining pr('liminary data with instruments

finder determine the ranges to these points. If an aiming circle

is not available, the azimuths may be determined by means of acompass, ano. the angles of site by means of an angle-of-site

instrument, although these instruments are less accurate.

221. Typical problem.-a. SUuation (see work sheet be-

low) .-The gun position being on Cook Hidge, the OP on Maxey

Ridge, and the lAr at the or, the data obtaineo. by means ofinstruments are as foUO\vs:

(1) OP to gun:nange equals 1,000 ~'ards.

Magnetic azimuth equals 3,500.

Angle of site equals -30.




-G~

1000 x E9.!)

J500

V!,OP-Gun

W !000l~o~30) -~o

Ueva-!:ion Gun. 100 S OP.13()

VI, OP-Tarse~

W Ih.M 1'30 x (-2.4)="39.11000 1000

tlevatlon OP=I~O~ Tar~et=90.9

VI, G T= 100 90.9: 9.r

1009

-30

3'00

lG30- 7 . +

""40

(2) OP to target:Range equals 1,630.

Magnetic azimuth equals 4,640.

Angle of site equals -24.

WORK SHEET: SINGLE or, TOG :METHOD

I. f~unJo," tion Cooll RIdge COlculcrl.ions

(I) -~rpat ~8xel/ Rid~e

2. J)O{4 from OP,

Jl..J.Ulm

{

:~: of site

~)_ ~l1%jmuthACIng ..

Angle of .it..l 'Io,n.tic o..imutho to !'lask

~t of site~1:t~0;;i'"uth.-------~~f:of lIite"'atnetic azimuth.

( 3. D~4 from "loUing.:5) Range, G t.o T 1500

RClng'c~G to MaskJ2.ange,G to Troop~

4. £Ievotion dO:~Q(calculQted.)I d. (-i)-- ~1:o,1't~t-rt -9.1 M= !OO~W

(5) ~:;' Ci to l' G.!M., Ii. to T 34.8

(G)- QlaoTarget 28.1

~/;oit~~oSkAS, G to 1"1Cl£ .... :::::::::::::::. ~h~~~kSlo,. _

~1~t'Q...e-~-:-:-c:e:::::::::::J'\askwill (will not) be cleQNaClearance oyer rcC\.'ciG to/tOOySVI, 0 roopsAS, G to 'l'roopeAE., Ii to Troope _.

Q'- to Tro0f.$

~~~!1~te{;/-A-'::'-gl-:::::::::::-=Troop .. will (will no..,.t)........:-:"e-r.""""'o.""te::---Cll1Ql'Clnce:over I'e«'d. S.A.

!. Direction clatQ'(7) JI1altlt..t.ic a ..imut.!r, G t.o T .5300

(0)_-8oa"o.n1Ie l.~

'{fi"J ng d.a4:C11 0 P(9) J )ase Arq:le L 1+00

~f:IfRt.ic: a~z.1~m-o;-n:th==5::S2:09:0=:::::=:

b. Rcquirenz.cn.t.-The firing data, to include the following:

(1) The QE (for laying in elevation).

(2) The lAP find base angle, and the magnetic azimuth

[If thp line gun-target (for laying in direction).

=~~~=

= =

- - -

~ _ ~ _

_ --

_ _

__ - _

~~~~

----- _ _ _

_ __




I

c. Plottillfl.-The data determined by the fir~-control instru-

ments can now be plotted any place under cover, as follows(fig. 68) :

(1) Draw a line on a sheet of paper representing a north

and south line. Select a point, 0, 011 this line to representthe OP.

(2) By means of a machine-gun protractor laid along this

line with its center at 0, plot the magnetic azimuths (angles'

i

I.

FIGURE 6B.-Plottlng, TOG, single gun

T

T

FIGUnE(In.-Line G-T

prolonged FlGunm 70.-DrawingN-S

linethrough G

frOIDnorth measured clockwise) of the lines OP-gun and OP-

targt.t, and draw the lines OG and OT.

(3) Plot G and'T on these lines, using any convenient scale,

such as the scale along the base of the protractor.

(4) Draw the line G-T, and, if practicable, prolong it until

it crosses the north-south line; call this point P. (Fig. 69.)d. Solution.

Step l.-The data relative to the positions of the g.un, OP

and lAP are entered on the work sheet.




Step 2.-The- data obtained by instruments at the OP are

entered on the work sheet.

Step S.-The range, gun to target, is measured, using the same

seale as used to plot G and T. In this case it is 1,500 yards.

Step (fig. 71).-Assuming that the elevation of the gun is

any arbitrary figure (for convenience, 100 yards is usually

taken as the gun elevation), by means of the mil formula

determine the difference in elevation (vertical intervals) be-'

tween OP and gUll.

R X 1Il 1000 X (-30)

, TV 1.000 1,000 -30 yards

Since the OP Is above the gun, the elevation of the OP equals

100 plus 30 yards, or 130 yards.

o U.I~0Y"nl.

Et '"J"rd.Q ~~~"=:3I-

I~ / ITtl.90.9J""'la9Jyorcla

----1500/",.J' ...

FIGUUE 71.-Determining angle of site, G-T

In the same manner, figure the difference in eleYatioll of the

OP and target.

RXlIl la/lOX (-2~)TV=' 1,000 1,000 -39.1 yards

Sirl('e the target is below the OP the elevation is 130-39.1

or 90.9 yards. Since the elevation of the gun is 100 yards

(arbitrary) and that of the target is 90.9 yards, the vertical

interval, gun to target, is 100-90.9 yards equals minus 9.1 ~.ards

(the target being lower than the gun).

Step 5.-Using the mil formula, determine the angle of site.

gun.target:

M= 1000 TV 1000 X (-9.1)

H 1.500 6.1

(Minus hecause the target is below the gun.)

St(~P 6.-The next step is to obtain the QE. From Table I,

Fire-control Tables, the angle of elevation for 1,500 yards is

found to be 34.8 mils. Since the QE is the algebraic sum of the

98053°-32--11 .

~

---- ----

=

_ ' -




angle of site and the angle of elevation, the QE is found to be(- 6.1) +34.8, or 28.7 mils.Step 7.~Determining the magnetic azimuth, gun-target:

(1) If the line GT, prolonged, intersects the north-southline, measure the azimuth directly, placing the center of the

protractor at the point P. (Fig. 69.) It is found to be 5,300mils.

(2) If the line GT does not intersect the north-south line

proceed as follows (fig. 70) : Convert the azimuth OG, 3,500

mils, to the back azimuth, 300 mils; measure the. angle OG'!

by means of tIle protractor. It is found to be 1,400 mils. It

will be ~een that the line gun-target lies 1,100 mils to the left

of magnetic north (1,400-300=1,100). The magnetic azimuth

of the line gun-target is now found by subtracting 1,100 frow6,400, or 5,300 mils.

Step B.-Determining the base angle when using the OP as an

lAP: Measure the angle OGT. This angle, Left 1,400, is the

base angle to be used if the gun is to be laid on the OP asnn lAP.

Step 9-Firing data.-The firing data are next entered on the

work sheet. They are as follows: lAP=OP; base angle=Left

1,400; magnetic azimuth 5,300; QE=29 (figured QE to thenearest ,vhole mil).

e. Use of an initial aiming point other than the OP.-Ilimpracticable to use the OP as an initial aiming point, any

object visible to both gun and OP may be used. The direction

(magnetic azimuth) and the distance of the lAP from the OP

are secured by the use of the fire-control instruments, and the

position of the initial aiming point is accurately plotted in the

same manner as described for plotting gun and target. The

base angle is measured by means of the protractor and thegun may be laid on the target by laying on the initial aiming

point, and turning right or left through the base angle.

222. Traverse method, TOG.-a. GenlCral.-In many situa-

tions it will not be possible to locate a single observation point

from which both gun and target can be seen. Itwill then be

necessary to run a traverse from the gun position, using one

or more OPs, to a point from which the target is visible. Forconvenience, OPs are designated as Ot, O~,0 8, etc., in the order

in which they are occupied. The methods used in surveying




are employed, data being obtained by the almmg circle, or

compass and angle-of-site instrument, and range finder.

, b. Obtaining data.-The officer who is to obtain the data

1lI0ves to a position 01

where he can see the target. 'Viththe aiming circle, or compass and angle-of-site instrument, the

tl1agnetic azimuth and angle of site from 01 to the target are

obtained. With the range finder he obtains the range. The

lJosition 01 is then marked by some means that will enable

him to locate it from his next position. He then moves to

some position where both 01 and the gun can be seen. His

Instruments are set up, and the range, magnetic azimuth, andangle of site from this position, 02 to 01 and to the gun are de-

termined. He then marks this position, 02 in such a manner

as to make it possible for the gun to lay on it as an lAP if

desirE'd. He can then go anywhere under cover, plot, and

calCUlate the data.

c. Plotting (fig. 72) .-The plotting is similar to that described

for the single or method. A north and south line is drawnat any convenient place on the paper. A point is made on this

line and markell 0\ The azimuths Ot-target and 01-02 (that

is the back azimuth of 0 2 to 0') are laid off. The position of

02 and the target are definitely located by laying off the ranges

on the lines drawn by means of some convenient scale, such as

the ~l<'aleon the base of the machine-gun protractor. 02 having

heen definitely located, a second north-and-south line is drawn

through 02 parallel to the north-and-south line through 0'.

1'he azimuth 02 to the gun is then lalU off and the position of

the gun is definitely located by laying off the range, 02_gun, as

above. The gun position and the target are then connected by

a line and the range gun-target determined by measuring the

line with the same scale.

d. Eleva.tion.-An arbitrary elevation (usually 100 :rards) is

given the gun position. The elevation of each successive point,

that is 02 0" anll target, is found with respect to the gun by

Using the mil formula. The difference in elevation of the gun

and target, or the VI in yards, may then be figured.

e. ])i.rcction.-The azimuth gun-target can be determined di-

rect from the plotted diagram by reading the azimuth of the

line at the intersection of either of the north-and-south lines.

'rhe hase angle can be read direct.

,

,




f. Firing data.-Firing data are figured in exactly the same

manner as previously described for the single OP method.

223. Mask clearance and troop safetY.-a. Oalculating clear-

ance from gUll position.-\Vhen the mask or frielHlly troops urc

NN

sFIGURE 72.-Plottlng. TOG, traverse method

visible from the gun, the clearance may be determined from the

gun position by computing the QE to the mask and subtracting

it from the QE to the target to see if the required clearance

exists; or, if the gun is already in position, the clearance may

be determined, without calculation, by using the sights on thegun.

~




(1) Oomputin.g cleamncc from gun. position.-By the use

of the rang,e finder determine the range to the mask or friendly

troops. Find the angle of site to the mask or troops .. Know-

tng the range and angle of site, the QE' may be computed.

l'he clearance is determined as described under map methods

by subtracting the QE to the mask or troops from the QE to

the target. The clearance thus found must equal or exceed

the mask clearance, or safety angle, prescribed in Tables II

and III, Fire-control Tables.

(2) Deterrnining olearanoe by u/~eof rear si{Jht.-(a) 'Vhen

gun is already in position, to determine the clearance by thellse of the rear sight, lay the gun to hit the target. Then

Without moving the piece, set the sight at the corresponding

range for mask clearance (or troop safety) as given in Tables

II and III, Firp-control Tables. If the line of sighting thus

established clears the mask (or troops), it is practicable to fire.

(b) If no tables are available, the procedure is as follows:

If the range to the mask is less than 500 ~'ards, set the sightllt the range to the mask plus 425. If the line of sighting

thus established clears the mask, the cone of fire will clear.

If the range to the mask is 500 yards or greater, set the sightat the range to the mask plus 3()()and see if this line of sight- .

tng clears the mask. If there are friendly troops, the proce-

dure Is similar. The sight is set at the range to the troops

Dlus Gm, or at 1,525, whichever is the greater. This givesresults which are sufficiently accurate for all practical pur-

Doses.

b. When mask or troops are not visible from {Jun.-The range

and angle of site from an OP to the mask or troops are meas-

Ured and the QE to the mask or troops computed from these

data as before. Mask clearance and troop safety are then

determined in the usual manner.

SF:CTION VI

OBTAINING DATA WITHOUT A MAP FOR GUNS

GROUPI~D IN BATTERY

224. Procedure.-a. Obtaining data.-Elevation and direc-

tion data are obtained exactly as prescribed for the single-gun

Inethod, lising one or more OPs. Data to locate both flanks of

targets having width are recorded. Data to the positions of

Loth of the flank guns may he secured from the OP nearest the



BASIC FIELD :MANUAL58

battery position and recorded for plotting; or data to thE' base

gun only, secured, and the position of the other flank gun of

the battery with reference to the base gun; that is, the magnetiC'

azimuth on which" the battery is to be placed and the relative

elevations of the flank guns, obtained for plotting.

b. The flank guns of the battery, ors, and targets (both

flanks of wide targets) are plotted to scale as described forsingle gun, TOG.

c. Tasks are then solved exactly as in the solution of a

map problem, except that vertical intervals are obtained asin single gun, TOG problems by means of the mil formula'instead of from map contours.

225. Hasty methods for distribution of fire.-a. When tJle

target front is approximately the same as the frontage of the

battery the direction data for the base gun only may be flgured

and all guns laid with this same direction, thus engaging the

target by parallel fire. The target may then be covered bytra versing the required amount.

b. When the target front is greater 01' less than that of

the battery, and speed is essential, direction data may be

figured as in a above and the target engaged by parallel cones.

This is a hasty method, and is wasteful of ammunition. It

should not be employed if sufficient time exists to figure

distribution of fire accurately.

SECTION VII

LAYn'G AND MAINTAINING LAYING

226. Direction and elevation.-Guns are always laill fordirection before being laid for elevation.

a. Dircction.-LaJing for direCtion is accomplished by meansof an aiming circle or compass, or by lAP and base angle, a~follows:

(1) Laying on base lines by means of an ai'11'l4ng circle or

compass.-(a) The aiming circle or compass is set up in any

Position with reference to the battery but not less than HiOyards from it. I

(b) All guns are ordered to lay on the head of the aimingcircles or compass, as an initial aiming point.

(c) The magnetic azimuth, aiming circle to base gun, is rentland converted to a back azimuth.

j

'

'




(d) The difference between the magnetic azimuth of the base

line and the magnetic azimuth base gun-aiming circle is the

angle through which the base gun must turn from the aiming

('in'Ie in order to lay on its base line.

(e) The base gun is then turned through this angle as de-~crilJed in battery drill.

!<IOURlD 73.-Paralleling guns by means of aiming circle or compass

(f) To lay the other guns of the battery, this procedure is re-

peat(!d for each gun. This automatically parallels all guns of

the hattery .. (Fig. 73.)

(2) Laying by means of an lAP and base angle.-(a) When

the huttery angle of parallax has been determined from a map-

1. The guns are all laid on the lAP with their dials andrear sights set at zero.




f. The amount each gun must turn nway from the base

gun in order to he varnllel is determined as de-"scribed in paragraph 215 h.

3. All guns being pa)'allel, they are then swung through

the base angle (fig. m) by means of the gradna tions

on the dial and }'£>l1rsight. They are then laid

for direction.

(b) 'Vhen the hattery angle of parallax: has not he('n <1e-

termineu from a map--

1. Each flank gun is llIo11llted and laid on the front sight

of the other.

2. ~'he traversing dials and f('ar sigllts are set at zero.

S. They are then laiu Upon the initial aiming point, and

the <lial and fear sights at'e read, thereby deter-

mining the nngle tllrough which they have moved.

~' The sum of these angles subtracted from 3,200 mils

will give the required battery angle of parallax:(fig. 74) : 1,OGO+2,llO=3,lGO. 3,200-3,lGO=40 (bat-

tery angle of parallax).

5. The guns are then paralleled and tUrJwd through the

base angle as described above.

(c) The mechanics of these methods are covereu in batterydrill.

(3) (a) La.yinf} by means Of lAP visible only to base f}un.-The base gun is laid on the lAP and moved to its base line

as expIahwd above.

(b) The traYersing dial and rt'ar sight of the base gnn re set

at zero. The hase gun is then turnpd through the angle ABC

(fig. 75) and laid on the other guns in turn, measuring the

angle ABC by means of the traversing dial anll rear sight.

Each of the other gur.s lays on the base gun with the traversing

dial set at zero. (\Vhenever guJlS lay on each other, each gun-

ner aims at the f"ont sight of the other gun.)

(0) The angle from the base gun through which the other

guns must turn in order to lIe laid parallel to the base line of

the base gun (:\0. 1 in this case) is the 'angle BCD.

Example: Assume that the angle ABC is 1,700 mils. Thpn

the angle BCD is tile differenee between 3,200 mils and 1,700

mils, and equals 1,GOO mils. The other gun then turns from

the base guu toward its own base line and sets off the angle

_




:BCD (1,500 mils in this case). It is then parallel to the base

line of the base gun. This method is known as reciprocal lay-

il lg• Any gun lllay be used as the base gun in thIs operation.

lAP

\

\

\

\\

\

\\

\

\\\

\

\

\\

\\

\\

\\

\\\\\

1

FIGURIII H.-Determining battery angle of paral-

lax by means of flank guns

~nstead ot employing an lAP the base gun may be laid by aim-ll.gcircle or compass and the other guns by reciprocal laying.

b. Elevation.-Guns are laid for elevation by means of clin-

tneterl'4. QEs are Het on the instruments, and the latter :IreIlaced on the right-side plate of the gun; arc to the rear if the

!,IJ:: is positive and arc to the front if the QE is negative.

~

~ ~



lG2 llASIO nEW ~IANUAL

227. Laying guns under cover of darkness.-When the gu

are brought into position for the first time at night the folIo«'

ing arrangements should be made during the day:, , ':

a. Drive a stake at the point where each gun is to be mounted

The stake should be of such height that the tripod may

mounted over it without disturbing the stake.

b. The necessary direction a11(lelevation data are obtaine.

by a suitable indirect-laying method.

c. Base and aiming stakes are set out by mounting an aimin'.drde in succession over each gun stake and measuring off

required azimuths.

l ~

/

///

/

///

/

'///

..........

'\\

C 1500

"FIGURE 75.-Lnying on base lines by menns of an lAP

Ylslble only to base gun

d. The g,uns are brought up and mounted over the

Luminous marks are placed on the base and aiming

which were set out during the day. A covered flashlight, 0lf

match, is used to set and level the clinometer.228. Maintaining laying; procedure.-a. To maintain lut

ing, base stakes (for base lines) and aimIng stakes (fof taSk')

are set out about 20 yards in front of the gun. The gunnef

must be careful to set his sights at 2,OO()before lining in all

stake. The sight should be left at this elevation, and the gUJJJner should check his direction frequently during firing.

b. From time to time, as between bursts or when changiIl~

a belt, the corporal checks the elevation by the clinometer. 11e

also checks the direction by means of the traversing, dial.

o. In order to minimize movement of the gun during firing,T bases, or an iplprovised foundation of logs or timber, should

n

.

b

th

stakes.

stakes,

.

,




be used with sandbags laid on the logs. Jamming handles

8hould be tight.

SECTION VIII

SEARCHING REVERS1<] SLOPES

229. General.-Searching reverse slopes is that form of fire

In which the bullets fall at such an angle to the slope of the

ground that grazing fire is produced. If reverse slopes had no

Inequalities or shell holes the maximum result would be

Obtainpdwhen the fall of the bullet was exactly parallel to the

ground; but since inequalities always exist, tIle best results

IVin be obtained when the angle of impact (the angle which

the trajectory makes with the slope of the ground at the point

Of imll:tct) is aPlH'oximately 45 mils. Any angle of impact

between 30' and GO mils will give excellent results, and good

results will be obtained with an angle of impact between 15 and

/(; mils. Data for such firing must ordinarily be obtained from

the map, although in exceptional cases the data may be secured

by TOG methods from an observation point. .

230. Determining the slope of the ground.-Scale the dis-

tance hetween two contours at extremities of the slope to be

/8earchcd. Using this distance, in yards, as R; and the VI be-

t'''een these contours, also in yards, as lV, substitute in the

h, lV X 1000 ..'lJil fOl'mula,M=-----

it

Exa1'n,ple.-The distanc:e bet,,;een two selected contours on the

~lol1eto be sCtil'ched seales 200 yards, and the VI between them

as Shown on the lIlap is 3G feet or 12 yards.' ,. lV X 1000' .

1Jf=--R--

1J f 12 X 1000

200M equals GO mils. (The slope of the ground.)

231. Finding the best position from which to search a re-

~erse slope.-a. By computation.-(l) Measure the angle of

~Iopeof the ground at the target and to this angle add 45 mils.

~ind the range which has an angle of fall corresponding to

this sum. On the map measure back this distance from the

target. If the position thus found is on the same level with thetarget, It is a suitable position.

(2) If the target is above or below this position, measure the

lingle of site and subtract it from or add it to 45 as the angle of

=



164- BASIC FIELD MANUAL

site is positiYe or negative. If the result is bet\yeen 15 and 75,

the position is suHable.

(3) If the resul t is greater than 75, move forward 100 yardS;

if less than 15, move back 100 yards and compute the angleof impact from the new position. Continue until a positioil

is found from which the angle of imr1act is Qetween 15 and

75 mils, preferably between 30 and GOmils.

(4) If impracticable to move the gun back and forth, 11

lateral moyement of the gun, keeping it at the same distanCe

from the target, may result in a sufficient change ill the angle;

j1100 1100 IbOO 1+00 1500 If>OO ITOO \600 1900 200~

RA/'IGf. lit YAIlO~

FIGURE 76.-Use 01' profiles anu graphs

of site to secure the de!Sired result. Thus when the gun is oIl

the side of a hill, a movement up or down the hill will change

the angle of the site without changing the range. ' .

b. By table.-See Table VI, Fire-control Tables.

232. Use of profiles and graphs.-To determine the possI'

hilith's for searching reverse sloves a profile is made to thesame scale as the trajectory chart (horizontally and verticallY)

on transparent paper. Place the profile of the ground over

the trajectory chart with the gun point of the chart on the

snrface of the ground as indicated by the profile. Move the

profile about, keeping the gun point of the chart on the profile

line and keeping the horizontal line of the profi.le parallel tOl-.

the horizontal lines of the chart, until a point is found wherethe trajectories strike the reverse slope at an angle greater

than the slope of the ground. Mark this point on the profile.

Referring back to the map from which the profile was made

the point is located. (Fig. 76.)

~



BASIC FIELD MANUAL

SECTION IX

DEFILADED FIRING rOSITIOXS

165

233. General.-a. Guns in firing positions on reverse slopes~rnploy direct or indirect laying depending upon the amount

Of defilade, tlle distance of the guns from the crest and

''"hether or Bot the target is visible from the crest. Thera

ar~ three cases:

(1) When the targpt is visihle from the crest and there is

~ight defilade only; that is, tIle line of sight is not defiladecl.

but all ()ther parts of the gun below the line of sight are(!eftlad('d.

(2) When the target is visible from the crest, the gun hav-

ing a greHtel' degn'e of' defilade than in (1) above and the

target can be spen by observer from some position in the

"icinity of the gun.

(3) When the target is not visible from the crest.

b. In the first ease direct laying is employed. In the lasttwo indirect laying is necessary. There is nothing new to

llt'escrihe in delivering fire from defiladed positions falling

\\'ithin case (1) or case (3), the former being purely direct

Ia.Sing and the latter indirect la,ying. Howeyer, the use of

llositions falling withi'n case (2) requires special consideration

!l~ the lllethods to l)e employed partake of the nature of direct

Ia.Ying,since dire('tion is established without the use of in-~truments, ~nd observation and adjustment of fire are made

hy the ohserver from positions near the gun.

c. 'l'he firing from positions falling under case (1) is known

a~ "sight d(>filade," while those falling under case (2) are

,knownliS "position defilade."

234. Position defilade.-a. A..drantagcs.-GUl1S in position

l!('filade fire" mnsked from ground observation and dirf'Ct fire.Generally the mask is sufficient to hide the smoke and flash.

~tovenH'nts in the vieinity of the guns are more or less un-

~~stricted and hence the problems of control and supply ara

~reatIy simplified. Normally guns can go into action much

ll.liCker,and with "less fatigue on the part of the gun crew,

i;ing POl'1itiondefilade than by ul'1ingany other position. This

e.<;pe<'lllllyrue when the Matthews cart is uf;ed.

b. Dilwd)vanfa"gcft.-The fire of guns in position defilade is

l'Ucticully ineffective against rapidly m"oving targets and tar-

~ ~



I

I

166 BASIC FIELD MANUAL'

~ets at close range, or with a' lal:ge negative angle of site.

Also, in order to lay on final protective lines, they must change

position.

c. Procedure.-The method of firing from position defilade

can best be illustrated by means of a problem. To facilitate

following this problem, refer to FigUr~77.

(1) A Problem (fig. 77).- (a) The section leader moves to

a position on the reverse slope where he can see the target.

lIe signals the squan leaders to join him,' ar.d while they afC

moving forward he determines the angle of site by means of

the angle-of-site instrument, and the target width by means

of the mil scale in the field glasses. lie finds the AS to be

plus 2 and the target width in n1i1s'to be 30. If friendly trooPS

are between his guns and the target, 'he detennines safety b1

applying the "leader's rule" from a position on the crest of

the hill, the reverse slope of which is occupied by his guns ill

position defilade. 'Vhen the corporals report he designates tb

e

target, obtains the range by estimation, taking the mean of tbe

('orporals' estimation and his own. lIe determines the range to

he 830 yards. lIe 'obtains the angle ..of elevation by referenCe

to Table I, Fire-control Tables; and' then' determines the Q1!J.lIe points out' the approximate locations for each gun, based

jn his knowledge of the QE, and gives bis fire order:

QE: PIus 13. .No.1: Traverse Left 20. . .

No.2: Traverse Right 20. .

At my signal.. .,.

( b) The corporals signal their squads forward, move to tbe

vicinity of the designated locations and select definite posl,

tions in position defilade. They use the cleaning rod,

on the toe of' the shoe with chin resting on the handle,' todetermine tbeheight of the gunner's eyes .. lIaving selectetf

definite positions they mark them by sticking the cleaning

in the ground. .

(c) Upon arrival of the guns the corporals lay them fot.

direction, by standing in rear, and com.manding "aiming stal\C

out." It may be necessary in some cases for the corporal~

to stand on several ammunition boxes' in order to lay theit

guns for uirection, or even resort to the method of two

servers, some distance apart, establishing the line by altef

nately dtrectin~ each' other Into line with gnn and target

.

.

'

plaCe(!

rotl

ob

'



------------ ------ .. -- ---~- ------ -~- - ----

W~I H T ll £ ~ rC TI OH l EA Il iR l IS N O T AT 'IlE

G II /I I P OS IT IO N, AS " NOW" I4ERE,HI DITERMINES

TU' A.'-(G-T)BY SlUCT'NG APOINT AS FA.AI' &O Vl , T Il~ T A~ GE T A Eo l iE I 5A DO V~ Y Il E G UN .

Itll: ~~OAT 850

A.S,. DITliIlf'l'"O 10 !Ii tA

~-:::~~~O~OI)ASME WAIO"S DURSt' TO~SIUlClT

(Face p. 166.) .



:!lASIC FIELD :MANUAL -167.

i'they_then place the QE .?R.. their guns and the gunners chec~k

e1earauce. .,>:

I(d) 'rIle gunners check clearance by sighting along .the

'''a tel' jacket, on line with the bore. .If time permits, th("

hOlt mny be removed and clearance determined by sighting

through the bore. If, clearance exists the Nos.. 2 signal

;I, :Ready." If clearance does not exist, the corporals move

the guns forward until clearance does exist;, but if prac-

ticable, not so far forward that the guns go out of position

lletilade. _,

(e) I,'ire is then controlled either by the section leader

{ll.the squad leaders.

(f) Where speed is an important factor, the section leader

Inny estimate the range, the angle of site (if the angle of siteIs small), and target width in mils (if his fingers are cali-

hr~ted). As his guns are moving forward he selects positions

for each. As each' gun arrives, he issues his fire order 'and

layS it for direction. .IIis 'fire order would -he:

. '{QE: Plus 13..~o. 1 gun Tra-yerse Lef.t _~.

. C?mn~enc~ ~ring. ,

{

QE: Plus'13.

NO.2 gun Traverse Rigbt 20.

o ,Commence firing. ,

'J'he sertion leader then would .adjust the fire of both guns.

'(2) New taruets.-Wlieri new targets appear the guns may be

khifted through ~heir respective angles of shift by commands

from the section leader (corporals are trained to zero their

dials and sights' on .the ;'fi~st aiming stake set out) who de-

termirlPs the angle by means of his field glasses, sitogoni-

Otneter, or calibrated fingers. The additional or reduc~d ele-

a.Uon required is estimated.

(3) Ob'8ervation and adjustment of fire.-In firing from po-

k1tion defilade, it is often desirable to get off the first burst

l\!ij quiekly' as possible and then adjust. If speed is demanded,

the accnrate determination of the QE and direction is not es-<'entia!. Observation of fire may be greatly increased by load-

Ilg belts with tracers. Generally one tracer to nine solid ball

suffielent. In situations where time is available, it is ob-

lous that accurate data ne('es.~ary to engage many targets, or

~

"

' -

~

~



168 • BASIC FIELD MANUAL

possible targets, can be Qbtained and guns camouflaged so as

to make them safe from all observation.

(4) The platoon as a batterll.-Platoons may use this methOdas a unit, controlled as a battery. Elevation is determined fot

one gun and applied to all. Direction is established, by tbe

platoon or section leaders, for all targets by quickly aligning

each gun on its approximate part of the target and causing aiJll'

ing stakes to be set out. Guns do not have to be paralleled as

in other methods of indirect laying nor is it necessary to de-

termine the battery angle of distribution or convergence. Ad'justment of fire can be made either by the platoon leader or

by the section leaders for their respective sections.. New tat'

gets appearing within the sector can be engaged quickly as

described above.

SECTION X

TRAINING O~ LANDSCAPE TARGETS AT 1,000 INCH ANlJ. AT UNKNOWN SnORT RANGES

235. Battery firing on 1,OOO-inch range.-a. General../

Battery firing on the 1,OOO-inchange instructs an organizatioO

and tests its efficiency in battery drill. In addition, it illustrateS

most of the technique of indirect laying and permits the gunnerS

to see the results of their firing, which is usually impossible 10

field firing. It should be used for instruction purposes prior to

battery firing in the field, as it requires a much smaller ammunl

tion expenditure. It should not replace battery firing in tlJe

field, however, except when lack of available terrain precludeS

field firing.b. Procedure.-(l) Target.~.-The targets used are the stanO'

ard Series A landscapes issued by the Ordnance

The method of setting up the targets is shown in Figure 78. JO

order-to economize in the expenditure of the upper panels Whiel

are the panels fired on, mimeographed reproductions of seleete

targets may be prepared and fastened over the proper target'

before each firing. .

(2) Mounting UU11.~.-Theguns are mounted on T bases se

flush with the top of the firing points. In order to permit fotliguns to fire on the same set of targets, the right T base shoUI

be opposite the first or second panel from the right and all 1bases should be as close together as possible. The guns at

laid with a clfnometer setting of •.ero, and then leveled

DepartmeJ}

'



170 . BASIC FIELD l\IANUAL

accurately as' pOssible by raising or lowering T bases as

required. !

(3) Targeting and obtaining "zel'o" quadrant elevations.-

The guns are targeted as for machine-gun mar~rsmanship, the

blank 1'0. 1 panel. LJeingtised for this purIJ{lse. All guns, hav~

ing been targeted, are laid with a sight setting of 441 ~!ards 011

an aiming point on the No.1 blank panel, which is on appro:x:i~

mately the same level as tIle gun muzzles. The elevations of the

guns with respect to the. horizontal are then read by means of

a clinometer, and these quadrant elevations are used for the

firing as the "zero". quadrant. elevations of the respectiveguns. For example, assume that it is desired to fire at a

point which is 8' inches higher on the landscape targets thanthe ahning point' '~~e'dto obtain the" zero" quadrant elevations.

The QE announcE'd in the fire order would be plm; 8 (an inch

at 1,000 inches LJeingequivalent to 1 mil). Assume also that

the" zero" qua(lr~ntelenlti()ns det~rmined as described above

for the four gnns we're No.\i b'Uh, 0; No.2 gun, pIns 2; No.3gun, minus 1; and Ko. 4 gun, minus 4. Since respective gunnersmust layoff plus 8 mils from, thetr '.'zero" quadrant elevations,

No.1 gunner .would set off QE plus 8; No.2, plus 10; No.3 gun,

plus 7; and No.4 gun, plus 4., '!l:c,

(4) Preparing 'd(J~a .for firi~g <t;;problem.-The officer in

charge of the firing must 'select sui fable targets and prepare

certain data ..for firing. The first, step is to determine the

magnetic azirriut]l 'of bas(! line; that is, the magnetic azimuth

of the line; base gun. (usually NO.1 gun) to its fl:ink of the

principal target., This magnetic azimuth is read direct by meanS

of an aiming~circlemotinted over the T base of the base gUll

before the guns ate emplaced.: A compass may be used if all

aiming circle i's'riot available. The target front of each target

and angles 'of' shift are likewise measured with the aiming

circle. The quadriu'lt elevations of the flank guns for each

target are o.btainedwith the aiming circle by measuring the

vertical angles 1>etwee'nhe aiming POi~t used for obtaining zerO

quadrant elevations ahd the respective flanks of the target.

The data rela"tive to target fronts, angles of shift, and quadrant

elevations of flank guns for each target may be obtained bymeasuring the distances in inches with a steel tape if desired,

or if no aiming circle is available., The guns having been

mounted, the battery front in mils is obtained by measuring the



BASIO FIELD l\:lANUAL171

distance in inches between the pintles of the No. 1 and No. 4

gUns.

NOTF..-These data would be obtained by plotting and calculation in

the normal service map or TOG problem.

c. A typical problem,.-Assume that it is desired to fire on

the targets indicated as '.rask A and Task B (fig. 78), and that

the following data have been prepared:

No.1 base gun; battery front 160 mils.

Base lines on Task A.:Magnetic aziml'lth, base lines equals 2,505 mils.

Ta,<l!c A:Target front equals 48 mils.

QliJ,all guns plUS 7 mils.

7'olollc B:

Angle of shift, equals Right 52.

,.rurget front, equals 25 mils.

QliJNo.1 gun, equals plus 13 mils.

Qg No.4 gun, equals plus 7 mils.'rhe panels are now covered with burlap screens and the

data are applied to the guns in the following manner: The guns

are laid on their base lines, using the aiming circle as an lAP

as dpscribed in paragraph 226 a (1). "Base pastel's," ordi-

nary black pastel's, are placed on th~ screen by Nos. 3 for

each bruno The gunners line-in these pastel's, using a sight set-

ting of 441 yards and the zero quadrant elevations. The bat-

tery front being 160 mils and '.rask A having a frontage of 48

mils, the battery angle of convergence for Task A is 160-48,

or 112 mils, and the gun :mgle of convergence is 37 mils. The

offieer in charge of firing therefore establishes aiming marks

Which are made on the burlap screen for each gun by No. 3

who Is lined in by the gunner. These marks are used instead

of aiming stakes and by the following command:

All guns on base pasters.

No.2, dial Right 20, sight Left 17.



Red aiming marks out.

Aiming marks are now established on the screen for Task B,

the commllnd to accomplish this combining the angle of shift,

Hight 52, with the gun angles of convergence for Task H, 45

j




mils (one-third of 135, the difference between the battery ft'ont

and the frontage of Task B), in the following manner:

All guns on base lines.





Blue aiming marks out.

Since the targets are so much smaller than the ground tar-

gets they represent, the guns are fired at the figured. quadrant

elevations r{'duced by only 1 mil with a search up of 2 milsand just enough traverse to have each gun cover one-third of

the target front. Gunners are instructed to fire bursts of five.

On this basis the commands for engaging Tasks A and Bare

as follows:

Ta.sk ..4..:

Lay on red aiming marks.

All guns QE plus 6.Traverse 12.

Search up 2.

At my signal.

Commence firing.

Task B:

Lay on blue aiming marks.

No.1 QE plus 12.No.2 QE plus 10.

No.3 QE plus 8.

No.4 QE plus 6.

Trallerse 8.

Search up 2.

At my signal.

Commence firing.

Upon completion of the firing, the screens are removed, the

results of the firing shown to all the men, and a thorough

('ritique given.

236. TOGproblems at unknown short ranges.-Single gun

and battery TOG problems may be conducted at unknown short

ranges on landscape targets. The problems may be solvedeither outdoors or indoors, and the accuracy of firing data

may be checked either with or without firing.




a. The set-u.p.-The landscape targets are used in the same

l1anner as on the 1,OOO-inchrange. A single gun or a bat-

ery is mounted on T bases at a convenient distance from the

argets as described for 1,OOO-inchiring. Additional landscapearget panels are placed between the guns and the target to

epresent friendly troops or mask or both.

b. Solution. of the 1J1'oblcm.-The targf't, mask or friendly

troops or both as desired, and one or more OPs having been

designated, data are obtained exactly as for a TOG problem

in the field except that a tape measure is used instead of a

range finder for measuring ranges, and all ranges are con-\>erted to yards by the use of any convenient range scale such.

!ls 1 inch equals 1 :rard. Angles of site from OP to the gun

or guns are measured to the bolt handle or to the approximate

height of a cartridge in the ('hamber. Data are plotted, fir-

ing data figured, and guns laid for direction and elevation,

e:x:actlyas for a problem in the field.

c. Ohecking solutiorl-8 without firing.-Guns having been laid

for direction and elevation, rear sights are run up to the cor-

responding ranges for mask clearance or troop safety and

Clearance and safety are checked by means of the line of sight-

ing. The panels representing; mask and friendly troops are re-

lUoved,and rear sights are set at the ranges to the target and

direction and elevation checked by looking through the sights.

d;. 01wcking 8oluHon8 b1l firing.-To fire the problem the guu

Or guns are laid for direction as for a TOG problem in the

lleld, and for elevation using figured angles of site only instead

Of quadrant elevations, the fall of the bullet for the short

ranges being so slight that it may be disr('garded.

SECTION XI

TESTS OF TRAINING IN INDIRECT LAYING

237. Purpose.-Tests of training in indirect laying will be

held for the purpose of determining the proficiency of machine-

gun units in the technique of indirect laying. .

238. Units required to fire.-Units equipped with machine

guns as a principal weapon are required to undergo the tests.

No unit larger than a platoon will be tested. The tests will

Consist of a problem or series of problems to be fired by one or

hoth Hcctions of the platoon.




239. When held.-The tests will be held after a course of nt

least one week's instruction in indirect laying.

240. By whom conducted.-The tests will be conducted bY

an officer designated by the commanding officer of the regiment

or separate battalion.

241. Ranges.-Whenever practicable the tests of training

will be held on ground with which the troops undergoing tM

test are unfamiliar. 'Vhen terrain is not available for firing test

problems in the field, the tests may be conducted on the 1,000

inch range by means of landscape targets.

242. Rules.-The officer ordering the tests will prescribe

~uch rules as he deems appropriate to suit local conditions .•. 243. Procedure.-T11e tests will be figured and fired under

the direction and supervision of the officer ordered to conduct

them. No prior information will be furnished the unit under-

going the tests other than the time and place of reporting.

244. Results.-A careful record of the results of the testS

will be kept. A written report will be transmitted by the officer

conducting the tests to the officer ordering them. No ratingwill be made. The officer conducting the tests will, however,

mention special point~ of excellence or defects noted.

-



CHAPTER 5

BARRAGES AND CONCENTRATIONS

,. 245. General.-In principle, guns within range of an enemy

should be ready and able to fire effectively upon designated tar-

gets. The machine guns lvithin an area fall naturally into two

classes: those in direct support of front line units, and those

forming a part of reserve battalions. The fire power of guns of

reserve battalions, guns which might otherwise be silent, should

he utilized whenever possible, in conjunction with the fire power

of maclline guns of assault battalions and of other supporting

weapons to fire barrages and concentrations: this accurate

and dense fire can be placed upon any point, line, or 1!-reawithin

range of the guns unless masked by an obstruction or by therequirement for t]le safety of friendly troops. In order that

the fire of machine guns and other supporting weapons from

severlll units may be properly coordinated for firing barrages

and ('oncentrntions it is usually necessary to place such firing

Under the dIrect control of one officer. The order designating

an officer to organize, control, and coordinate barrage and

eoncentrntion fire should include the units to participate, thefire missions, and the general locations from which units will

llellvt:>rtheir fire. This chapter covers the uses of barrages

and ('oncentrations, and the manner in which this fire is de-

veloped when ordered by a commander.

246. Barrages defined.-a. A machine-gun barrage is a bar-

rier of fire consisting of the organized, controlled, and co-

ordinated fire of several guns which are usually arranged inbatteries of two or more guns each. The beaten zones of

these guns are laid down on a line, or series of lines, to deny

the enemy a passage through the area of fire. The whole line

having been designated, it is then divided into sections of appro-

llriate size an(1 allotted to each battery available for. the

mission. Barrages may be moving (rolling) or stationary

(standing) ; they may be used offensively or defensively. The

175




delivery of fire may be by direct laying, by indirect laying,

or by a combination of both, depending upon the type of fire

which is most suitable for the mission to be performed.

b. A normal barrage is the barrage of primary importance

for which each battery is laid at all times except when actuallY'engaged upon other missions. This fire is usually delivered

close to friendly troops to screen and protect them by inflicting

losses on the enemy, and by keeping down or preventing his

fire. '.rhe line to be covered by fire should be placed as close

to the friendly troops as the requirements of safety. and the

selection of suitable ground will permit. Fire is <lelivered at

once upon call, usually by signal from the appropriate area.It is the barrage usually fired during an enemy assault~

o. In a box barrage the fire is applied to two or more sidesof a position in such a way as to isolate it. It is generallY

used to cover raids on enemy positions. \Vhen used in con-

junction with artIllery, machine guns may be employed to

place a standing barrage on one or more sides of the box, or

to thicken the entire artillery box barrage. It is a form ofthe standing barrage.

d. A rolling barrage is fire appU('d progressively in distance

at indicated intervals of time to successive lines. It is a forDl

of accompanying fire seldom practicable for machine guns. This

is due to the impossibility of searching many reverse slopes

and the difficult problem of clearance of friendly troops on all

lines that a rolling barrage may reach. Lifts by machine gunsare made from 200 to 500 yards at a time, ('ach lift being cal-

culated as a new task and not determined from the data for

the first firing. 'Vhen machine guns are employed with other

weapons their fire is placed approximately 400 yards ahead

of the nearest line of light artillery high explosive shells.




247. Concentrations de:fi.ned.-A concentration of machine-

gun fire consists of the organized, controlled, and coordinated

fire of several guns, usually arranged in batteries, for the pur-

pose of neutralizing or demoralizing an area known or thoughtto be occupied by the enemy. This definition of a concentration

::

=

;;

:FlGURID 79.-l\Iacbine-gull normal barrage

must be borne in mind in contradistinction to barrage fire in

whleh each gun and each battery have a section of the entireline as a separate task upon which they fire to deny the ground

under fire to the enemy.248. Organization of guns.-a. Best results can obtain only

when the guns available for barrage and concentration missions




are .organized as a whole and their fire directed in accordance

with a general plan. Time permitting, the guns which must

employ indirect laying methods are organized into batterieS

FIGURE 80.-Machine-gun box barrage

of two, three, or four guns each, the platoon of four gunsbeing the usual battery. Batteries within a group are lettered

from right to left. Two or more batteries constitute 11 group,




the company being the usual' group, the company commander

being the group commander. Groups are numbered from right

to left. Two or more groups may constitute a separate com-

mand. The plan need not follow definite lines of organiza-tion. Its most essential features are contrul and flexibility.

Th~ organization is of a flexible nature created on the spot and

1esigned for very definite tasks and missions.

FIGunE 81.--=-l\lachlne-gun concentration

b. The organization for the purpose of firing concentrations

and barrages is brought about by the commander who designates

the fire missions to be engaged, the unit~ to engage them, and,

in f4(>mecases, the positions which units will occupy. In the

usuul case he will also designate an officer to perform the neces-

sary duties in connection with organization, coordination, and

control. Time permitting, this information can be disseminated

by the use of an organization chart. (Par. 252.) However,




where speed is a primary con8ideration it may be built up as

time proceeds. (Par. 251.)

c. The duties of this officer are as follows:

(1) To organize the guns available into. batteries and groupS.

(2) To designate approximate positions for each group.(3) To designate fire missions for each group in accordWlce

with the tactical plan.

(4) To assure an adequate supply of ammunition and arrangefor its distribution.

(5) To provide for communication and control.

(6) To maintain contact with the troops supported, his unit

commander, as well as his batteries and groups.d. The duties of the group commander are as follows:

(1) To designate positions for each battery.

(2) To prescribe the fire missions for each battery.

(3) To carry out the plans for ammunition supply, communi-('ation, and control.

(4) To maintain contact with the troops supported, the bar-

rage commander, and each battery.e. The duties of the. ba ttery commanders are as follows:

(1) To compute the fire data for his battery.

(2) To prepare battery and gun charts.

(3) To supervise and conduct the fire of the battery, taking

all precautions necessary to provide clearance over friendlytroops.

(4) To arrange for observation and adjustment of fire when-ever such action Is possible.

249. Coordination.-a. Maximum efficiency results only

where there is eomplete coordilla tion betwpen aU- the guns of

an area, and with the guns of adjacent areas .. Further, the

fire of all weapons must be coordinated, the most effective use

being exacted of each. The fire of the artillery, of the Infan-

try mortar, the final protective lines of front area guns, as

well as the guns assigned to barrage and concentration fire

missions, must all be considered as one problem. Hasty or-

ganization can not, of course, permit all of these factors, but

time permitting they are vital considerations.

b. In an organization involving a number of batteries, the

placing of all guns on identical fire missions would be unwise;

it would restrict the number of tasks too greatly because only



t


a small number of tasks should be assigned to each battery,

and it would be wasteful of ammunition. Targets which may

be engaged by frontal fire by one battery may be engaged by

oblique, or even enfilade, fire by another; some batteries will

be able to fire more effectivelY upon certain tasks than others.

All of these factors must be considered in building up and

llerfedlng the plan.250. Control.-a. General.-The dominant factor in barrage

fire is control. Unless the commander has the power of plac-

ing the fire of the severnl batteries where and when he de-

sires, the whole plan has little value. This is the greatest

}lroblem. There are several' methods of maintaining control,

(.ach one being appropriate under certain circumstances.

b. Time schelLulcs for conduotinu fire.-This method gives

the clock time of opening fire, the duration, and the rate. It

is particularly applicable for the initial stages of an attack,

for harassing and interdictory fire. Its disadvantage is its

lack of flexibility ..

o. An observer for each uroup or each battery equippelL with,

some' method. of rapid ana relia,ble OOrlul1unicaU,on.-The use

of this metho<l enalJles an olJserver to watch for suitable oppor-

tunities to engage each target, and then bring dovm the fire.

The normal barrage must lJe handled in this way. There are

several methods of communica tion whleh give satisfactory re-

sults under conditions suitable for their use.

(1) Pyroteohnio siglla18 given by rockets, flares, or 001• ..45

'Pi.~tol traccrs.-The use of a pyroteehnic code must be simple,

it must be restricted to a few signals, and, above all, it must

l)e coordinated with other arms and units which are using this

method of control.

(2) Any metholL of 'Visual signaling .

. (3) Me.~sen,gerR1Dithin reasonable limits of di.'Jtance.

(4) Telephone communication. when availa.ble.-Connecting

several batterIes in series on one line reduces greatly the

amount of wIre necessary for this purpose. Speed and flexibil-

ity are greatly increased when the telephone is used.

251. Engagement of surprise targets.-a. Speed in securing

<lata and opening fire may be developed to a very satisfactory

degree by following the sequence outlined below:

(1) An observer (reconnaissance officer or other qualifiedperson) is sent forward to a point from which he can see the

..




target, taking with him an aiming cirde, range finder, nnd

some method of communication. (Par. 2[,0.)

(2) The several batteries are mounted in 'a suitable position

from which they can fire.

(3) 'Vhen the observer arrives at his position each batterYcommander determines the range, the azimuth, and the angle

N

FIGURE 82.-Data secured and plotted at the bat~

tery pordtlon

of site from his base gun to the observer. These data are thenplotted at each battery as shown in Figure 82, and the elevation

of the observer computed with relation to the base gun.

(4) Base lines are then established and base stakes set out

iO that the base gun is laid on the position of the observer.

(5) In the meantime the observer is using his instruments to

secure the direction, the azimuth, and the angle of site from

his vosition to the targets, to probable masks, and to friendly




troops. This information is transmitted to the batteries by any

lnethod of communication. (Par. 250.)

. (6) Each battery commander then proceeds to plot the data,

completing the form shown in Figure 82, solve the problem,and determine the fire data for 1lis own battery as explained

In parllg:raphs 220, 221 and 222.

(7) F'ire can then be opened and controlled as explained in

llUragr<lph 2[)0.b. It is seen, therefore, that finy problem capable of solution

by the use of otle OP (pars. 220 and 221) ean be solved with

~l)eed and with "accuracy without 'the battery commander leav-ing his battery at. any time, nor need he see the targets at all.

Similarly, any traverse-method problem (par. 222) may be solved

by the battery commander going only far enough forward to get

'the data from the or nearest the battery to the battery, and tothe observer rather than to the targets. Speed is developed by

the several steps proceeding concurrently rather than in series;

that is, the battery commanders select positions and mount theirguns while the observer moves forward;. the former secure and

Dlot the data to the obsenei:. while he is taking the data to the

targets. Just as soon as the observer furnishes. partial informa-

tion, perhaps the data for one. task, the batt~.ry commanders

eomplete the plotting .ba~d 'on Figure 82 for that mission and

Secure fire data. The development of speed is limited only by

the sldll of the officers and th~eefficiency of the communica-tion system available. ,

c. An alternate method equally satisfactory, to i>;:used when

the traverse method of securing data. (par.' 222) is necessary

consists of the reconnaissance offi~er, selecting his initial orat some point from which all batte~ies ar~ visible. lie can

mark this position in some suitable manner and proceed. 'Vhen

he reaches a point from which he can see the target he sends

back data on the location of his OP with relation to his 0 1

(direction, distance, angle of site) in addition to target data.

The batteries are laid on the position of the 0 1 and the plotting

completed on the data furnished by the reconnaissance officer.

The UReof this methoa eliminates any necessity for battery

commanders leaving their batteries for the purpose of securing

fire data under any conditions.

d. The use of this method enubles new or additional targets to

be engllged in a very few minutes once the set-up is completed

~




which adds the desirable factor of flexibility. The development

of organization charts, battery and gun charts, as well as tbe

coordination of the entire plan can then proceed while tbe

several tasks are being engaged by flre.

e. The accuracy of this method of determining fire data is

dependent upon the use of aiming circles Which have been

P"c~entf,.ont line

£nemyfront line

FIGl'UB: 93.-overlay to accompany Annex No. I,

Field Order No.6, IIq. 29th Inf., 6 May 30

properly declinated, and the necessary corrections made foreach azimuth reading.

252. Barrage charts, overlays, diagrams.-The use of the

organization chart shown below with an accompanying over~

lay (fig. 83), sketch, or diagram is an excellent means of trans-

mitting information about the composition of the command,

the location of its elements, the assignment and location of

tasks, the rate of fire, amount of ammunition required, andthe means of control.



BASIO FIELD MANUAL 185

253. Tasks.-a. A task is a fire mission to be covered by

one or more batteries. Tasks are designated by letter either

from right to left or from front to rear.

b. The principal factors to be considered in the selection of

tasks for batteries are-

(1) The location of the battery.

(2) The area within range of the battery.

(3) The safety of friendly trOOlls.

(4) The possibility of securing frontal, oblique or enfilade

fire as desired.

o. The location of tasks may be indicated 011 a sketch, an

overlay, by coordinates, or by general description.

254. Task frontages.--a. The maximum task frontage which

shoull! be assigned a single gUll should rarely exceed 50 yards,

decreasing to 25 yards as conditions become unfavorable. The

area which can be covered effectively by one gun within a

given time limit depends upon the range, the slope of the

ground at the target, and the rate of fire.

b. A battery of four guns can cover effectively a task 200

yards wide and 100 yards deep. I

255. Rates of ftre.-a. It Is important that a definite rate

of fire be prescribed for each task for strict observance by all

concerned, for the following reasons:

(l) A great amount of ammunition is usually required. iu

a barrage. Careful estimates of the ammunition based on therate of fire required must be made to prevent waste and to

permit the gunner to complete a task with the available am-

munition by firing the designated number of rounds per minute.

(2) The guns will not function properly when firing at au

increased rate over an extendeu periou of time. It is neces-

sary to insure time for oiling t11e gun and to keep the water

jacket filled. In addition, there must be sufficient time fort11e gunner to relay, anu to accurately traverse or search or

both. '1'he normal rates of fire are-

(a) Slow rate.-About one-fourth box per minute. This is

the rate used for prolongeu fire.

(b) Medium rate.-About one-half box per minute. This

rate is used for fire lasting not longer than 30 minutes.

(0) Rapid" rate.-About one box per minute. This rate isused when the situation demands it, but can only be maintained

for n few minutes.

9SDG3° - - 32- - - - 13




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1:1

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tIoqm I ~8 I~ ~nmmti '[UlOJ, .... '<> .;.... e.Ellnu!Ul I liS I liSJad spunoll .. .....

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~. In addition to the points mentioned heretofore, the follow-

factors must be considered in determining the rate of fire:

(1) 7'actieal requirernents.-In preparatory fire deliveredst prior to the attacli:, the rate of fire may be rapid for. a

IV minutes and then decreased according to the mission of'

barrage and. other considerations. A normal barrage may

delivered at a rapid rate for about three minutes and then

wed down. The rate for harassing fire is usually about

OOrounds per hour. This fire is ordinarily intermittent and

y be carried out at any rate. ,(2) Prontage per gun.-The rate of fire will normally be

nsidered in connection with the assignment of frontage.

(3) Length-. of time of the barrage.

(4) Ammunition available.

c. In order to facilitate calculations and to insure the trans-

lssion of the correct information as to the number of rounds

be used in a minute, rates of fire are always entered in

r1'age organization charts and on other ch.arts, and orders

ren in barrage fire, by stating the number of rounds per

lnute.

256. Forward moves.-a. Arrangements may be made for

e forward movement of groups and batteries to new positions

om which they may continue to support the assault echelon

an attack beyond the range possible from the initial posi-

ms. These changes of position should be made by successive

belons. When these changes of positions are ordered, ma-

ine-gun units should push forward rapidly to commanding

ound from which direct or simple indirect laying methods

n be utllized to provide swift and adequate support; com-

icated barrage and concentration plans are not feasible.

le safety of friendly troops requires constant and careful

nsideratlon.

b. Forward movements must be preceded by a reconnaissance

r an. officer with several runners to select routes, provide for

liding units to their positions, warn them of shelled areas,

cate targets, and calculate fire data.

c. Careful consideration must be given to the distance sep-

'ating tbe machine-gun company from its own battalion which

st not be so great tbat it can not quickly rejoin when'dered.



188\

BASIC FIELD MANUAL

257. Antiaircraft defense.-rrhe best method of providing

protection against aircraft is by the careful concealment of

the position from aerial observation. The protection of the

guns by concealment may be augmented by utilizing some gunSsited primarily for antiaircraft defense.

258. Subsequent action.-Upon completion of missions the

subsequent action of units is determined by the plan of attacl{

and nature of the expected resistance. The organization phll1

must include provisions for the subsequent action of machine"

gun units. l\Iachine-gun companies may-

a. Rejoin the battalions to which they belong.b. TIe assigned new missions such as the protection of

:flank or to assist in the consolidation of ground won.

1



INDEX

Paragraph Page

A.ccelerator, backward action oL____________________________________ 39 22

Accessories. See Spare parts and accessories.Accidental discharges 109 71

Adjustment of gun and tripod 124 78

Aiming point, use of prescrihed--------------------------------- 110 71Ammunition, inspection oL 125 79

AntiainTaft defense ~_______________________________ 257 188

Assemhllng, sequence in_____________________________________________ 9 5

Assistants to officer in charge of range practice; duties________________ 114 72

Backplate, how removed • 8 4

Barrages:Charts, overlays, and diagrams • • •• 252 184

ControL_a. 250 181

Coordination • •• .------ .-- 249 180

Defined • • • • • 246 175Engagement of surprise targets .______________________________ 251 181

Forward moves . 256 ]87

Organization of guns •• 248 177

Hates of fire • • 255 185

Barrel:Packing 01. 21 14HenlOved, how 8 4

Barrel extension:Allllemullng_. •• • • 17 11Disassemhling; detailed instructlons_____________________________ 16 11Henloved how ._. 8 4

Beaten zone • • • • ~. 133 82

Belt-filling machlne ._ •• • • 57 34

Blackening slghts • • 87 62

Illank ammunition attachments • • .__________________ 58 37

Bolt:As.'lembllng- • • • 13 8

Backward movement oL •• .__ 40 23Disassembling; detailed instructions_____________________________ 12 7Forward movement oL • • 44 24

Hemoved how • • .__ 8 4

.Bolt bandle, bow removed •• ._ 8 4

BrownIng machine gun. See Machine gun, caliber .30, M1917.

Classes of fire with respect to:Oround • • • -. --.--- 143 89

Oun •• • ., • . -.- 141 87TargeL ••• _. • • --.- 142 88

Coach; duties and use •• • ._._.__________________ 86 61

189

-- ---- ------ ---------

--------------

____ _ _ __ __ _

----

----------

-

__ --- -- - ------- -

--- ------ ----

--

----- - ------ -- - -----

- - - ---------------

----

__ - - --- -- - - -- -

__ ---- --- -- -

__ - -- - ---

__ __ __ -- -- --- -

~

__~----- __-- - -

__

__

-- - - --- --- __ - ----- -----



t.

190 INDEX

Para~raph PageCocking action_ 42 23

Cold weatber, care ot machine gun In . 25 17

Company commander 79 59

Cont'entratlons:Coordination -,__ 249 180

Defined_ 247 177

Forward moves__________________________________________________ 256 187

Organization of guns_____________________________________________ 248 177Rates ot fire_ --------_ 255 185

Cone ot fire__________________________________________________________ 132 82

Cooling system______________________________________________________ 2 1

Courses to be fired:

Instruction practice________ 76 58Modifications__________ 76 58

One thousand Inch range________________________________________ 75 57

Preliminary practice_____________________________________________ 76 58

Record practice____________________ 76 58

Cover:Assembling_____________ 19 12

Disassembling; detailed Instructions_____________________________ 18 12

Removed bow___________________________________________________ 8 5

Data, obtaining without map tor guns grouped in battery:Hasty methods ot distribution ot fire ._ 225 158

Procedure • :l24 157

Data, obtaining witbout map tor single gun:

GeneraL_______________________________________ 219 149

Mask clearance and troop safety . 223 156

TOG, single OP method; procedure_____________________________ 220 149

Traverse metbod, TOG_________________________________________ 222 154

Typical problem___________________________ 221 150

Detlladed firing positions:GeneraL eo" 233 165

Position defilade____________________________ 234 165

Demonstrations, arrangement oL____________________________________ 121 76

Direct laying:

Comparison witb indirect laying_________________________________ 130 81

Definition_ --------------_____________ 127 80Elements involved_ -_______________ 128 80

Relation ot marksmanship_______________________________________ 129 80Value 131 82

Direct laying on landscape targets at 1,000 inches: .Direction__________________ 189 122

Final protective lines and sectors ot fire__________________________ 192 123GeneraL 183 121

:Mounting guns 185 122

Overhead fire c • 191 123

Problems -. 1\)0 122

Ranges . • 188 122

Sight setting .. • 187 122

Targeting .' ,____ 186 122

Targets , • 184 122

_ -

__ ___ __ - - __

- __ __ _ ___ _ __ __ __

_

___

___ _

_ __ __ __ _ __ __ __

__ _ _ ___ __ ___ ___ __ __ __ __ __ __ __ __ __ __ __ __ ___ __

_

__ ---- __ _ _________ _______

___ __ _ ___ __

_ - __ - - -- - __ _ __ __ __ __ _ _ ___ __ __ __ __ __ __ ___ _

_ ----- _ __ __

-- - - - - - -- - ___ _ __ ___ __ ----

- __ - __ __ __ ___ __ _ __ __ __ _ - - --- - - - - ___ __ _

__ _ _ _ __ _

__ _ _ ___



I NDEX 191

ireet laying problems: Paragraph Pagel<'ire-order problems 182 116

Instruction, preliminary 181 116

Purpose and scope 180 116Isassembling; general rules_________________________________________ 7 3

squalification; record practice_ 115 73

~lving spring, action oC____________________________________________ 43 24

lUipment; range practice__________________________________________ 81 59

Bed beIL__ 3 ?,

Beding:First act ot. 41 23

Section action or.________________________________________________ 47 27

nal protective line:T)efinition 166 104

Laying gUll at night and during fog and darkness________________ 170 105

Methods oflaying on____________________________________________ 169 104Pro(~edure in flring .. 171 106

Termin, influence oC____________________________________________ 168 104

Ire:Classes of. See Classes of fire with respect toObservation and adjustmenL____________________________________ 92 63

Ire control:Adjustment of fire_______________________________________________ 176 IIIChain or. 175 110

GeneraL 174 110

Ire distribution:Auxiliary aiming mark •• 155 98

Combined sights 154 98

GeneraL 148 91

Importance of proper 149 92

Oblique tllrgets, methods of engaging____________________________ 152 96

Point tan~ets or targets covering small areas, methods of engaging_ 153 97

Targets tllken in enfilade, methods of engaging___________________ 151 94

Wide tllrgcts, methods of engaging_______________________________ 150 92'ire for adjmtmenL 139 86

'Ire orders:Basic elements .______ 178 112

Exanlples . 179 113

Purpose_ 177 112Use .__ 84 61

Iring after COIIlTJland or signal to cease firing________________________ 111 71

as attack, Cllre of machine gun during______________________________ 26 17

un and amlllunition Ilsed in record practice________________________ 107 70

!tinS, elTect of proper location oL___________________________________ 144 89

read-space a(ljustmenL_ 11

tlunediate lldion:Definition

J) u ties -.

l'ha.~es of.

28

29

32

18

18

111

-- ------

_ _ _ _ - - - -- - - -- -- - - - - --

__

___ __ -

-- -- - - -- - -

------

----- -------------

- ---- --

- - - - - --- --------

----

__ _ _ __ __ _ ___ __ __

_____ ___ ____________

__ __

- -- ------ -- ------------- --- - ---

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - --

-- ---- ---- --- --- -----



i

Machine gun, caliber .30, M1917:

Assembling, sequence in •••• _._._ ••••••• ••••• ••••••••• _.... 9

Barrel extension, assemblin~-.- ••••• ---_ •• ••• ••• •••••••• 17

Barrel el.tension, disassembllng •• ._ ••••••• •• _. ._ •• _... 16Barrel, packlng • • • _. • • • •••••• Jl

Bolt, assembling ._ •••• ._. ••••• _. ••• ._. • • 13

Bolt, detailed disassembling _. • ._. ••••• _._ .•• ._ •••• 12Care; genera1._. . •• _._. ••••••••••••••••. •• •••••••• •••• 23

Landscape targets, training on, at I,OOO-lnch and at unknown shortranges ••••••• _. • • ._. _. •• •••••• ••• •• •• ._ 235, 236

Latch, how removed • • •• •• •• 8

Latch spring, how removed_._ •• •• • • • ._...... 8

Laying and maintaining laying: .

Darkness, laying guns under cover ot._. .• ..•.• ••_... 227

Direction and elevation •• • •• •• • • •• 226

Procedure .• •• 228

La)1ng the gun •• • • •• •• •• •• • • ••• ••••• 89

Loading and locking action. • • •• _. • •• • ._.___ 46

Lock frame:A8."embllng_ •••••• •• • • ••• _._ ._._ •••• ••••• • ••••• 15

Disassembling; detailed instructions_. ••••• ••• ••••••••••••• _. 14

Removed how •••• ••• • ••• ••• • ••• ••••• ••• _........... 8

Immediate action-Continued.' Paragraph

Relaying ••• ._. •• •••••• •••••••• _._ ••• ••• _..... 30

Removing a case from the chambt1r ._ •• ••• ••• _............. 35Removing round from T sloL • •• • ••• 34

Ruptured cartridge extractor •• •• •• • .. •• •• _. 33Scope of instruction • ._ • . • •• ••••• • 28

Stoppages, firing with ._ ••• ._ •• • • e. 31

Test in ._. •• _. ••• ._ •• • ._. • • •••• 36'

Indirect laying:Comparison with direct laying ••• •• •• _._._ •• ._._ ••••• _._ ,203Data, basic • • • • • • ._ 208

Data, sources of. _. • ._. •• 204

Definition ••• ••• •• _. • 201

Fundamentals • _. 207

Organization • • ••• 206

Proficiency, requirements (or ------.-_-- •• • • ._ •• .___ 205Tests of training in_ •• _. • ._._. 237-244

Theory of • •• • ._. : •• ••• 207,208

Uses •••••••• •••••• ._ •• _. •• • • 202

Inspection, time for •• • • • _. • e ••• •••• 106

Instruction practice:Adjustment •• _. • • • • .__ 94

Com blnation •• _., • ._ ••• _. •• • • 98

Combined searching and traverslng • • • 97Grou plng •• •••• ••• • ._, _. •• • • 9:3

Searching ••• •• • • '. _. • ••• • • ••• 95

Traversing •• _._ •• • •• . • •• •••• 96

Instructors, ad vice to •••• _._ •• •••••• •••••• •••••••••• • 120-126

192 INDEX

Page18

21

1918

18

21 !

f126 ,

132 i126

1125 i

127 I126

126/

173,174,

127-132,

125 \~O

66

6868166!67 :

68:

168-1~1

51

162 [

158

162

621

:: IJ111

11

14

8

115

_ _ _ _

__ __ __ _

__ "__ __ __ __ __ _

- __ __ __ _

- __ _ _ _ _ __ __

__

__ _ _ eO_e •• •• • _ _ • __ • ._ •••• ••• ~._ . _.

__ __ __ __ __ _ ' __ __ __ __

_ __ __ _ __ __ _ _

_ _ __ __ __ _ _

__ _ _ _ _ _

_ _ __ _ __ __ _ __

__ __ _ __ __ __ __

__ __ _

__ ________ ____ ______ ____

__ __ __ __ __

__ __

__ _._.

' __ __

__ _ __ _ __ __ _ __ __

__" __ __ _ __

~

j

' j

1

7~

1



I NDEX

Machine g,un-Continued. ParagraphCold weather, care in • • •••• •• •• 25

Cooling system. • •• • • • .______ 2

Cover, assem bling • • 19

Cover, disassem bling . -__ 18

Disassembling; general rules • •• •• 7

Disassembling of parts dismounted only for repair ••• 20

:Feed belt • • • • •• • • -. 3

Gas attack, care during . ~_ 26

Gmlllral data • • • •• 5

Gun and tripod, care llnd eleaning_______________________________ 27llead space adjllstment. • .___ 11

IIllIllcdi!lte actioJl • • 28-36Lock fmme, assemliling_________________________________________ 15

Lock frame, disassembling .____________________________________ 14Mechanical functioning • • 37-48M (mnting • .______________ 4

Parts, methods of changing .______ 22

Points to be observed before, during, and after firing .______ 24Hernoval of groups from gun • • ._.___ 8

Heplaeing groups in gun • • .__ 10

Sights, front and rear • • • ._. .__ 6

Spare parts and accessories • ._ 55-58StoPllUges • 4!}--52

'l'rlpod IIlountings • • 53,54Type • • 1

Machine-gun fire:Direct laying. technique oL • • •• 127-200

Indirect ;ayin~, technique oL • 201-244

Malfunetions, unusuaL • -------______________ 51

Map duta for guns grouped in hattery:Method of o!Jtaining • 211

Ordllrs . • •• •• 218

Proeedure • 214

Re(IUirement. •• _. ._______ 213

SituatiOlL • . ._.___ 212

Solution of Task A~ .___________________________ 215

Solution of 'I'1\sk n______________________________________________ 216

Solution of 'rusk c______________________________________________ 217

Map data for single gun:Method of obtaining • •• ._._. 209

Typical probleIll • eo. 210

MarkslllRnship, IIlllchine-gun::FurHlarncntals_. • • e. _._•• •• • ._. 60

Inst.ruction, met.hods oC ... ._. •••• • 61

I'rllparatory exercises • • • •• •• ••• 63-74

193

Page

17

1

1212

3

13

2

17

2

17

5

18-229

9

22-27

2

14

15

4

5

233-37

27-31

31,32

1

80-124

125-174

27

140

148

140

140

140

141

145

147

132

133

39

40

41-55

Officer In charge of range practice. • ._. 77,101,114 58, 70, 72Order of Instruction and record practice • •• 102 70

Organization:Range .~_ •• 123 77

\V ork • • .__ 122 77

__ __ __ __

- - ----- ---

-

__ __ -- --- __ __- -- - --

__

-

- -

- -

- _ - _______

__ _ __



194 INDEX

Overhead fire: ParagraphField glass, use in applying safety rules. • • • • ._._. 163GeneraL • • • •• • • •• •• _. 156

Gunner's rule._. • ._. e . •• • _ .' 159

Leader's rule_ ••• ._______ 160Minimum clearance_ • • • • ., 157

Precautions. .• •• •• _. •• 165

Procedure after friendly troops reach limit of safety • ._. .• 162

Procedure before friendly troops reach limit of safety. • • •• 161Safety angles_. -----. • • ••••••• _. • 158

Troop safety zones •• • • • • ._____ 164

Parts, methods of changing. • • ••• ••• •• 22

Personnel at firing point • •• •• •• 85

Personnel at guns; record practice_. ••• •• _. • • ._ 104Preparatory exercises:

Duties of leaders • • ._______ 64

Equipment for each squad • • •• .________ 65

Examination • • •_. • ._ 74

~ranipulation e. • • • • 73

Position • • •• • • 70

Sighting and aiming, first •• • •• •• ._. ._. •• 66

Sighting and aiming, fourth_. • •• • •• ._ ••• • • 69Sighting and aiming, second_. • • •. _.__ 67

Sighting and aiming, third ._. •• • ••• 68Sight setting. • • ••• • • •• 71,72

Range cards:

Attack ------_- • • • ._. ._ ••• e. . _... 173

Defense_ ._._. _. e. • .. _. . _._. 172Range construction • •• • • ._. • _._... 116

Range determination and windage_. • • ••••• _. ._ 134-140Range finders. ------. • • •• ]38

Range officer -. ••• ---.-. ._._ ••• _._ ••• ._ ••• • ._. 78Range practk-e, conduct of • • • •• ._. • • 77-99

Ranges:Classlfication • • ._. _. e . • 135

Detelmination, methods of • •• _._. .______________ 136

Estimation, training in • • •• ._.__________ 137

Recoiling parts:Backward movement • • • • • •• • •• .__ 38

Release of -------.--- • • • • •• ._.____ 45

Record practkoe, rules governing • • ._._._ •• • ._ •• •• 100-115Hetargetlng -. ----------.---- e. . . . . .. 103

Reverse slopes, searching of:Determining slope of ground_._. • • ._. • •• 230Finding best posltlon • ._: • • • •• • 231

General_. .-.-.------ •• •••• ••• ._._. • •••• 229Profiles and graphs. • •• •• _._. ._. • •• •• 232

Ruptured cartridge extractor, use oL •• • ._._____________ 33

Safety precautlons----. •• • • • _. • •• • _. 80

Sandbags:Pre~ration aud use • •• • ••• ._. •• •• •• 118

Ran~e practice. ••• --.--- •• 82

Page

102

99

100

101

99

103

102

102

99

103

14

61

70

42

42

55

50

47

43

47

45

46

48,49

109

106

73

84-86

86

59

58-69

84

85

85

22

24

6~73

70

163

163

163

164

19

59

75

60

I

__ __ __ __ __ _____

__ - --------

-

__ - - - __ __

__ __ _ __

__ _ _ _

__

__

- - ----

- - - - _. -----------

__

__ __ _ _

- - - ~ __ __ __ - - - ----- __

__ - - -

---- __ __ __

'

__ __ __ __ __ _

- - - __ __ __

- - ___ __

__ __ - - --- __

_ __ __

--- --- -- __ __ __ " __ __

- - - - -- eo. •••• •• _ •• _._._ __



126

56

57

58

55

50

52

49

51

00

113

258

I NDEX

SCoring rules • ~:~grait~

Sectors of fire; definition_____________________________________________ 167

iI~~~~~~~~:::::::::::::::::::::::::::::::::::::::::::~Spare parts and accessories:

)

Barrels, adequate supply to be maintained

Barrels, care of.

Belt filling machine

Blank ammunition attachmentsChest.

Stoppages:Classes

Classified table of

GeneraL

Malfunctions, unusuaL

Range practice

! SUb~~:o::t~~~~~~ :::: ::: :: : : : __

I 'l'arget designation:Bursts of fire_ 146

Leader laying the gun___________________________________________ 146Oral deslgnation_ 147

Tracer ammunition____ 146

, Training, preliminary___________________________________________ 145

l ;~~~:~~~g the gun_. 113

, Machine-gun target A; instruction practICe 93,94

Machine-gun target B; instruction practice______________________ 95Machine-gun target C; instruction practice______________________ 96

Machine-gun target D; instruction practice______________________ 97

Machine-gun target E; instruction practice______________________ 98Oblique; methods of engaging_ 152

One thousand inch, construction ot._____________________________ 119

Point; method of engaging_______________________________________ 153

Taken In enfilade, methods of engaging__________________________ 151

'l'rainlng on landscape, at 1,000-inch and at unknown shortranges 235,236

Used on 1,000-inch range_________________________________________ 91Wide, methods of engaging_ 150

'rask frontages ._____________ 254

'l'asks deflned .____________ 253

l'bases:Construction and use________________________ 117Range practice • .____________ 82

'rechnique of machine-gun fire:Direct luylng. 127-200

Indirect laying • 201-244

'rest.; of training in direct laying:

Condueted by whom.___________________________________________ 1961 feld when_. _._.____________________________________ 195

195

Page

71

104

7170

2

79

33

34

37

33

27

30

27

27

62

72.188

90

90

90

90

90

60

66

6768

68

68

96

75

{7

94

168-17363

92

185

185

75

60

80-124125-174

124

124

~ ~

f _

~ _ _ _ _

~ _ _ _ _ _

_ _

~------------------------

_

__ _ __ __ _ __ __ ___ __ __ __ __ __ __ __ ___ __

_



196INDEX

Tests of training of direct laying-Continued. Paragraph'

Procedure •• -.---.-.--------.- •• _. • ••••• •• _. "__ 199Purpose. •• • •••• _._ •• •• _. •• ..... • 193

Ranges_. •• --.-. -'-- • • ••• .. •.• ._ 197

Results --.--- -----. -.---- • .' '. ._. ._. ._____ 200

Rules_. • •• -.----. _'" •• _' , •• • •• .__ 198Units required to tire • •• _. •• •••• 194

Tests of training in indirect laying:

Conducted by whom. • .• _. • ._. • 240

Held when. ._. • • •• _. ••• _._._ •. ,_. •. _.___ 239

Procedure_ •• -.------- -'.-- .• • ..• _. ..... 243

Purpose .---- •• •• • ._ •• •• ._. ._ •• .. 237

Ranges •• ---' ••••. •• • • ._________ 241Results • •• • • •• • .______ 244Rules • •••• • .. _. •• • 242

Units required to tire •••• -.---. --. • • •.. • • •• 238Time Iimits •• • • ._. • •• • • 88

Trigger action. • •• -. .. • . . 37,48

Tripod; care and cleaning ..... •• ••• _. • .______ 27

_ ' __' __ __ __ __ __

- ---- - __ __ __ __ __ __

----- _ __" __ __ __ __

__ __ __ __ ~-- __

--- __ _ __ _ ----- --

__ ----- --------- __ __' __ --- __

__ __ __ ---- __ __

__ -----

-

basic field manual volume iii-1932

Documents