downloaded from http://www.everyspec.com on 2010-01-25t16:18:56

8/14/2019 Downloaded From Http://Www.everyspec.com on 2010-01-25T16:18:56.

1/71

Downloaded from http://www.everyspec.com on 2010-01-25T16:18:56.


2/71

Chan ges in force: C2 and C3

FM 23-11C3

Change HEADQUARTERSDEPARTMENT OF THE ARMYWashington, D. C., 28 April 1970No. 3

90-MM RECOILLESS RIFLE, M67

FM 23-11, 6 July 1965, is chang ed as follows:Page 4. Paragraph 3 a (6) (as chan ged by C2 ) issuperseded as follows:

(6) Maximum effective range:HEAT, TP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400 metersAntipersonn el. . . . . . . . . . . . . . . . . . . . . . . . . . . 300 meters

Page 4, paragraph 3b. A column for antiper-sonnel is added as follows:

(1) APERS.(2) 6.79 pounds.(3) 3.97 pounds.(4) 1250 feet per second.

Page 6,paragraph 8b (1) (c). In line 2, clock-wise is changed to read counterclockwise.

Page 16. Paragraph 20 is superseded as follows:

20. ClassificationThere are three authorized rounds for the 90-mmrecoilless rifle, M67. These are TP M371, HEATM371E1, and 90-mm canister , XM590E1. The tar-get practice (TP) round is not stand ard, bu t it isavailable for issu e in certain a reas. It is ballis-tically id entical to th e high explosive an titank(HEAT) round but contains only a small spottingcharge as the projectile filler. The 90-mm canister

rou nd , XM590E1, is a fixed typ e antip ersonn elfound which functions at muzzle action.

1



3/71

2



4/71

Page 17. Paragraph 21.1 is added after para-graph 21.

21.1 90-mm Canister, Antipersonnel,XM590E1

a. The 90-mm canister, antipersonnel round isdesigned for close-in d efense against m assed at-tacks or assaults on personnel positions. The can-ister consists of a thin-walled, deep-drawn, scoredaluminum body which contains a payload of 2400eight-grain, low-drag, fin-stabilized, steel-wirefragments called flechettes. The complete car-tridge weights approximately 6.79 pounds. Theprojectile weights approximately 3.97 pounds andhas a muzzle velocity of approximately 1250 feetper second.

b. The aluminum cartridge case (M112) is 16.29inches long and weights 1.0 poun ds. A flange atthe base contains a plastic rupture disc that ob-structs the gas flow during the early stages of pro-pellant combustion. When the prop ellant is ignited,the rotating band on the base traps the propellentgases, building up an internal pressure whichbleeds through the holes in the base. The built-uppressure bursts the body with the payload from

By Order of the Secretary of the Army:

Official:KENNETH G. WICKHAM,

Major General, United States Army,

The Adjutant General.

the case when the canister leaves the rifle. Thescored aluminum body strips back and the eight-grain flechettes are released, dispersing in a coneangle of approximately 8 degrees.

Warning: Overhead firing is prohibited.Page 17, paragraph 22b. In line 5, (lucky ele-

ment) is deleted.Page 20, paragraph 28. In line 2, radiological ischanged to read nuclear.

Page 20, paragraph 29c. In line 2, radiologicalis changed to read nuclear.

Page 46. Paragraph 69 c (1) (c) (as superseded byC2) is sup erseded as follows:

(c) Zero the rifle at a know n ran ge between350 and 400 meters, or u se a d istance wh ich is 80percent of the most distant target.

Page 46. Paragraph 69 d(1) (c) is superseded asfollows:

(c) Zero the rifle at a know n ran ge between350 and 400 meters, or u se a d istance wh ich is 80percent of the most distant target.

Page 53, paragraph 76 g. In line 2, except whenfiring at a moving target is deleted.

Page 53, paragraph 77 c. In line 2, or antiper-sonnel is added after TP.

W.C. WESTMORELAND,General, United Stat es Army ,Chief of Staff

Distribution:To be d istributed in accordan ce with DA Form 12-11 requ irements for 90-MM Recoilless Rifle, M67.

3

U.S. GOVERNMENT PRINTING OFFICE: 1994 O 160-412



5/71

FM 23-11*C2

CHANGE

No. 2

HEADQUARTERSDEPARTMENT OF THE ARMY

WASHINGTON , D.C. 19 September 1968

90MM RECOILLESS RIFLE, M67

FM 2311, 6 July 1965, is changed as follows:Page 4. paragraph 3 a (6). "Maximum effectiveran ge450 meters." is chan ged to read "Maxi-mum effective range400 meters."Page 5. Paragraph 5 b is superseded as follows:

b. The reticle is an optical glass disc with an0.749-inch ap ertu re etched with a m etric scale. Itis graduated at 50-meter intervals at ranges up to

400 meters, and nu mbered every 100 meters up to800 meters. Speed -lead in d icator lines are p ro-vided at 50-meter intervals u p to 400 meters andat 100-meter intervals from 400 to 800 meters. Thevertical range line is extended through the 0 line

to form a boresight cross. The broken horizontallines are speed-lead indicators. Each line or spacerepresents 2.5 mph of apparent speed. The curvedlines are stadia lines, and are used to estim ateranges to targets of known dimen sions. The aver-age tank is 20-feet long and 10-feet wide; there-fore, the stad ia lines h ave been calibrated tocoincide with these dimensions from 100 to 600meters of range. A level vial at the bottom of thereticle provides a zero cant reference for the tele-scope so that it m ay be kept level when boresight-ing and firing the weapon (fig. 3).

1*This change supersedes C1, 5 April 1967.



6/71

Page 5. Figure 3 is superseded as follows:

Page 6.5.

Paragrap h 5.1 is add ed after paragrap h

5.1 Direct Fire S igh tTelescope, M 103A1a. The M103A1 sight (fig. 3.1) is a modified

version of the standar d M103 sight. The mod i-fication h as been m ade to th e right side of thesight reticle and is to be referred to only w henfiring the XM591 round. The value difference of

Page 5. Figure 3.1 is added as follows:

the range line has been mad e so that it matchesthe trajectory of the XM591 round.

b. On th e mod ified sight, the range line on th eright side of the sight reticle is graduated in 25-meter intervals from 0 to 200 meters and every 50meters from 200 to 400 meters. The value of thelead lines remains un changed.

Note. The XM591 round was an experimental type am-munition and is no longer issued. However, the M103A1sight will be found on some 90mm recoilless rifles.

2



7/71

Page 6, par agrap h 7. Title "Instrum ent Light,T25" is changed to read "Instrument Light, M54"Page 17, paragraph 22. Title. "Fuze, PIBD,M530" is chan ged to r ead "Fuzes, PIBD, M530and M530A1"

Page 17. Paragraph 22 c is added is follows:c. The M530A1 fuze is a modification of theM530 fuze. The M530A1 fuze has a mechanismwhich gives it a greater arming delay time.Page 17. Paragraph 23 is superseded as follows:

23. Subcaliber Devicea. The su bcaliber dev ice (fig. 16) for the 90mm

recoilless rifle permits realistic gunner and loadertraining and eliminates the use of expensive serv-ice ammunition. Because targets are not destroyedas they wou ld be if service ammun ition w ere used,

range maintenance is reduced.

Page 18. Figur e 16 is supersed ed as follows:

b. The M49A1 subcaliber device (fig. 16.1)consists of a long, cylindrical sleeve, a barrel, abushing w ith an integral hinge, a locknu t hous-ing, a firing pin : and attaching hardware. The de-vice utilizes a case blow-out principle throughsix equally spaced holes in the chamber shoulder

section of the barr el. These holes perm it thecartridge case to be blown out, and limit the p res-sure w hich in tu rn lowers the v elocity to matchballistically the major caliber round.

c. The trajectory of the 7.62mm subcaliber car-tridge is abou t the sam e as the ma jor calibercartridge; however, there is a telescopic reticlemismatch. When firing tables III and IV tozero the M49A1 subcaliber device, the systemshould be zeroed at ap proximately 80 percentof the maximum range of the targets to be en-gaged in order to minimize absolute mismatch at

any point in the trajectory.

3



8/71

Page 18. Figu re 16.1 is add ed as follows:

Page 21. Paragraph 30 c (2) (b) is rescinded.

Page 25, paragraph 44 a. In line 4, "breechblock"is changed to read "lockring."

Page 40, paragraph 62 b. In lines 2, 3, and 4, It

extends 140 feet to the rear an d has a 180-footbase, 90 feet on either sid e of the b ore axis ex-tended. is changed to read : "It extend s 43meter s to the rear an d h as a 55-meter base, 27.5meters on either side of the bore axis extended";in lines 6 an d 7, "90 feet" is changed to read "27.5

meters"; in line 11, "50 feet" is chan ged to read"15 meters."

Page 43. Paragraph 68 b. 1 is added as follows:b. Additional Ammunition Requirement. Prior

to firing the q ua lification tables, the su bcaliber d e-

vice w ill be zeroed u sing nine rou nd s, firing th ree-round shot groups when firing tables I and II.Firing tables II and IV, the su bcaliber d evicewill be zeroed using six rounds. Only the initialfiring order will zero the device. All succeedingorders w ill fire two confirming zero roun ds.

4



9/71

Page 41. Figure 32 is superseded as follows:

Page 46, paragrap h 69c (1) (a). In line 4, "200 Page 46. Paragraph 69 c (1) (c) is superseded asto 450 meters" is changed to read: "150 to 350 follows:meters." (c) Zero the rifle at a known range between

250 and 300 meters, or use a distance which is 80percent of the most distant target.

Page 46. table III. In the Range (metric) col- Page 47, table V. In the Range column "250400" is changed to read "200350 (trial 2); "

i

350each trial 110). 450" is changed to read "300400" (trial 3).umn, "200450" is changed to read "150350" (for

5



10/71

Page 50. Figur e 38 is supersed ed as follows: Page 50. Figure 39 is superseded as follows:

Page 57. Paragraph 93 b is superseded as fol-lows:

b. When firing tables III and IV, it is recom-mended that the su bcaliber device be zeroed at a

By Order of the Secretary of the Army:

range of 80 percent of the most distant target inorder to eliminate the requiremen t for zeroing ateach sp ecific range, and to redu ce the mismatchbetween the trajectory and the sight reticle.

Official:

W.C. WESTMORELAND,General, United States Army,Chief of Staff.

KENNETH G. WICKHAM,

Major General, United States Army,The Adjutant General.

Distribution:To be d istributed in accordance w ith DA Form 12-11 requ iremen ts for 90-MM Recoilless Rifles, M67.

6



11/71

*FM 23-11


DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited.


12/71

CHAPTER 1

INTRODUCTION

1. Purpose an d Scopea. This manual provides information for train-

ing personnel to operate the 90mm recoilless rifle,M67. It includes mechanical training, fire controlinstruments, spare parts and equipment, mainte-nance, ammunition and fuzes, crew drill, marks-manship, technique of fire, and advice toinstructors concerning the weapon. The materialpresented herein is applicable to nuclear and

nonnuclear warfare.b. For information pertaining to detailed disas-sembly and assembly, refer to TM 9-1015-223-12.

c. Doctrine in FM 7-11 on the tactical emp loy-ment of the platoon antitank weapon applies tothe 90mm rifle, M67.

d. Users of this manual are encouraged to sub-mit recommend ed changes or comments to improvethe manual. Comments should be keyed to thespecific page, paragraph, and line of the text inwhich the change is recommended. Reasonsshould be provided for each comment to insure un-

demand ing and comp lete evaluation. Commentshould be forwarded direct to the Commandant,United States Army Infantry School, Fort Ben-ning, Ga., 31905.

2. CharacteristicsThe 90mm recoilless rifle, M67, is a lightweigh t,

portable, crew-served weapon intended primarilyas an antitank weapon. It can be employed in anantipersonnel role too. It is designed to be firedprimarily from the ground using the bipod andmonopod, but it may be fired from the shoulder.It is an air-cooled, breech-loaded, single-shot riflethat fires fixed ammunition. The rifle is equippedwith a manually operated breech mechanism and apercussion-type firing mechanism. It is designedfor direct firing only, and sighting equipment forthis purpose is furnished with each weapon (figs.l and 2).

3. Tabu lated Dataa. 90mm Recoilless Rifle, M67.

3



13/71

(1) Weight:Complete system (unloaded) -- 35 poun ds.

(2)(3)

(4)(5)

(6)(7)

Telescope with mount andinstrument light ------------ 2 pounds.Overall length ------------- 53 inches.Height ground mounted(approx) ----------------- 17 inches.

Maximum range (approx.) -- 2,100 meters.Maximu m range (as deter-mined by sight grad uations) - 800 metersMaximum effective range --- 450 metersRates o f fire ---------------- Rapid : 1 round

each 6 seconds,not to exceed 5rounds.

Sustained : 1round per min-ute indefinitely.

Note: When firing the rapid rate of fire, a 15-minutecooling period must be observed after every five rounds.

b.Ammunition.

(l) Type used ----- HEAT ----- TP.(2) Weight of roun d 9 pou nd s--- 9 pou nd s.(approx.).

(3) Weigh t of pro- 6 pounds--- 6 pounds.jectile(approx.).

(4) Mu zzle velocity 700 feet per 700 feet per(approx.). second. second.

4



14/71

CHAPTER 2

MECHANICAL TRAINING

Section I. FIRE CONTROL EQUIPMENT

4. General

In order to keep the M67 operating effectively,all crew m embers mu st know the following:

a. Disassembly and assembly of the weapon tothe extent authorized.

b. Comm on causes of stoppages.c. Immediate actions to clear the weapon.d. Maintenance procedures.

5. Direct Fire SightTelescope, M103

The 90m m rifle is equipp ed w ith the M103 sightfor d irect

-

fire. There is no prov ision for an in-direct fire sight since this weapon is not designedfor an ind irect fire role.

a. The M103 telescope h as a fixed-focus, 3-pow ermagnification, and a field of view of 10 (fig. 3).

b. The reticle is an optical glass disc with an0.749-inch aperture etched with a metric scale. Itis graduated at 50-meter intervals at ranges up to800 meters, and numbered every 100 meters up to

800 meters. Lead lines are provided at 50-meterintervals up to 400 meters and at 100-meter inter-vals between 400 and 800 meters. The top verticalline is extend ed th rough the 0 line to forma bore-sight cross. Lead lines and spaces, each represent-ing 5 mils, are prov ided horizontally for 30 milson either side of the v ertical centerline. Sixtyl-mil spaces along the 800-meter range line andtwelve l-mil spaces along the v ertical axis are pro-vided for small adjustments to the line of fire.Stadia lines are provided for ranging on targetshav ing a 10- or 20-foot dimension. A level vial atthe bottom of the reticle provides a zero cant r efer-

ence for the telescope so that it may be kept level(fig. 3).

5



15/71

c. A circular red glass wind ow is provided inthe w all of the telescope housing, ad jacent to thereticle, to enable both the r eticle and level vial tobe illuminated. The red glass permits illuminationwith a minimum loss of target contrast.

6. Telescope Mou nt, M 110

The telescope m ount, M110, (fig. 4) holds thetelescope, M103, to th e w eapon . The telescopemount is designed so the telescope can be insertedand seated rapidly and with assured replacementaccuracy. The mou nt a lso features screws w hichenable boresight adjustment of the telescope withrespect to the weapon in azimuth an d in elevation.The telescope mount, M110, fits in the front bracketassembly.

8. Disassem bly of the Breech an f Hin geMechanism

7. Instrument, Light, T25The sight reticle of the M103 telescope can be

illuminated (fig. 5). A dovetail slot on the tele-scope receives the lamp bracket of the instrumentlight. The instrum ent light is pow ered throu gha lead w ire by tw o BA42 flashlight batteries in thebattery case. A rheostat kn ob on the en d of thebattery case turns the light on and off and controls

the amount of illumination of the sight reticle.

Section II. DISASSEMBLY, ASSEMBLY, AND OPERATION

a. General. Operator and organizational (d)

maintenance of the breech and hinge mechanismsis limited to operations covered herein; for allother maintenance, notify maintenance personnel. (e)

b. Breech and Hinge Mechanism Components.

(a)

(b)

(c)

6

(1)Disassembly.Make sure the weapon is clear and not (f)

cocked.With the breechblock in the closed and (g)

locked p osition unscrew the firing pincap (1, fig. 6) and remov e it and thefiring pin spr ing (2, fig. 6 and fig. 7).Rotate the safety (3, fig. 6) 45 degreesclockwise from the FIRE posit ion;pu ll up and remove (fig. 8). The

hinge block end of the cable assemblyis now free.Pull the h inge block end of the cableassembly forward and remove it fromthe hinge block (fig. 9).Unlock and open the breechblock.Push d ownw ard on the hinge pin (4,fig. 6) and remove (fig. 10).Remove the extractor link (6, fig. 6)and the extractor (7, fig. 6).To prevent the sear from d ropping

down and blocking the lockring, holdthe breechblock with the hinge portionup ; dep ress the detent plun ger (10,fig. 6), rotate the lockring (8, fig. 6)counterclockw ise, and rem ove (fig.11).



16/71

(h)

(i)

(j)

Turn the breechblock over and remove (a)the sear (9, fig. 6 and fig. 12). (c)Remove detent plunger and spring (10,fig. 6 and fig. 13). (d)Insert the small end of the hinge pininto the rearward end of the breech-block housing and tap the firing ham-mer (11, fig. 6) and ham mer bush ing(12, fig. 6) forw ard until free of thebreechblock housing. Remove the fir- (e)ing hammer and hamm er bushing fromthe front of the breechblock hou sing. (f)

(2)Assembly.(a) Holding the breechblock with the

hinge portion up, install the firinghammer (11, fig. 6) and hammer bush-ing (12, fig. 6).

Replace the sear (9, fig. 6).Replace the detent plunger and spring(10, fig. 6).While holding th e breechblock w iththe hinge portion up, depress the detentplunger and install the lockring (8, fig.6), turning it clockwise until tight;then turn counterclockwise until twodistinct clicks are heard.Install the extractor (7, fig. 6) and theextractor link (6, fig. 6).With the extractor link in its full ex-

tract position, install the breechblock,making sure that the hinge portion ofthe breechblock enters the opening inthe hinge block and engages the recessin the extractor link.

7



17/71

(g)

(h)

(i)

(j)

Aline the hinge pin h oles in the breech-

block and hinge block, then install thehinge pin (4, fig. 6).Install the cable assembly in the hingeblock with the n otched portion thatwill mate with the safety facing awayfrom the r ifle tube.Position the recoilless rifle safety 45degrees clockwise from the FIRE po-sition, pu sh dow nward , and rot ate itclockwise to the FIRE position.Install the firing pin spring and firingpin cap.

9. Principle of Recoilless Op erationThe recoilless principle is based on th e escape

of a portion of the prop ellant gases to the rear ofthe w eapon . The escape of these gases is con-trolled no movement of the weapon occurs(fig. 14).

8

10. Mechanical Functioning

a. In order to keep the 90mm rifle operatingeffectively, all crew mem bers mu st un derstand theprinciples of operation and functioning of theweapon and its various parts.

b. Mechanical functioning is divided into threeclasses:

(1) Opening the br eech.(2) Closing the breech.(3) Firing the piece.

c. Discussion of functioning may start with anyof the three phases. Assuming that a cartridgehas been fired, phases then occur as shown in b

above. This represents on e comp lete cycle offunctioning.

d. Opening the Breech.(1) Unlocking. As th e lockrin g (8, fig. 6) is

rotated clockwise to unlock the breech-block (5, fig. 6), a cam surface on the



18/71

(2)

interior of the lockring (8, fig. 6) comesin contact w ith th e sear (9, fig. 6) an dmoves it inward . The cam su rface exertspressure against the firing hammer (11,fig. 6), forcing the firing ham m er an dfiring p in spr ing (2, fig. 6) rearw ard .As the lockring (8, fig. 6) is further ro-tated clockwise, it is arrested by the d e-tent p lunger (10, fig. 6) and at this pointthe breechb lock (5, fig. 6) is un locked.

Cocking. The weapon is normally cockedby opening the breechblock; however, theweapon m ay be cocked w ithout openingthe breechblock. This is accomplishedby rotating the lockring to the unlockedposition and then rotating it back to the

locked posit ion without opening thebreechblock. When th e lockring is ro-tated to the un locked p osition and thebreechblock is swung to the open position,it pivots o n th e hin ge p in (4, fig. 6). Atooth on the inner hinge portion of thebreechblock engaged in a recess on theextractor link (6, fig. 6) cams the extrac-tor link and extractor (7, fig. 6) rearwardout of the chamber.

e. Closing the Breech. As the breechblock isswu ng to the closed position, the tooth on the innerhinge portion of the breechblock retracts the ex-tractor link (6, fig, 6) and extractor (7, fig. 6)into the cham bers. As the lockring is rotatedcounterclockwise to the locked p osition, the cam

9



19/71

surface on the interior of the lockring allows th esear (9, fig. 6) to move outward and become en-gaged with the hinge block end of the cableassembly.

f. Firing the Piece. When the breechblock isswung to the open position the recoilless rifle

safety autom atically positions itself to the safeposition. To fire the w eapon the safety mu st berotated from the SAFE to the FIRE position.When the trigger safety is depressed the trigger

assembly is unlocked. As the trigger assembly issqueezed pressure is app lied to the bottom of thecable actuating lever which pivots on the springpin and imparts a pull on the cable assembly. Asthe cable assembly m oves forward , the hinge blockend oft he cable assembly releases the sear allowing

it to move forward und er pressure from the firingpin spring. As the firing hammer is released, thefiring pin spring propels the firing pin against theprimer, firing the projectile.

10



20/71

11



21/71

12



22/71

13



23/71

14



24/71

Section III. MALFUNCTION S, STOPPAGES, AND IMMEDIATE ACTION

11. Malfun ctions and Restoration of Balance

When a recoilless weapon functions properly, itdoes not m ove w hen fired. The forces acting on th erifle neu tralize each oth er and the rifle is balanced.If there is a major movement (either forward or

rearward) when the rifle is fired, it must be sentto maintenance for restoration of balance.

12. Terms

a. A stoppage is an unintentional interruptionof the cycle of operation .

b. Immediate action is the unhesitating applica-tion of a probable remedy to reduce a stoppagewithout considering the cause of the stopp age.

13. Stoppages

Prevention is the best solution to all stoppages.

When the crew comp letely understands the op era-tion of the weapon and app lies normal care andfrequent cleaning, the most comm on typ es of stop-pages seldom occur. By making frequent checksand inspections, the crew insures the d etection ofworn or broken parts. Some of the more comm onstoppages causing the 90mm rifle to function im-properly are:

a. Failure to Fire. This stoppage may becaused by

(1) Defective primer of the ammunition.(2) Weak or broken firing pin spring.(3) Broken or deformed firing p in.(4) Accumulation of carbon in the firing

mechanism.(5) Broken or maladjusted firing cable.(6) Failure of breechblock to lock.

b. Failure to Cock. This stoppage may becaused by

(1) Broken or damaged sear or sear catch.(2) Broken or damaged cable assembly.

c. Failure to Extract. This stoppage may becaused by

(1) Broken or damaged extractor.(2) Broken or damaged link assembly.

(3) Deformed cartridge case.(4) Broken or damaged tooth on breechblock

hinge.d. Failure to Load. This stoppage may be

caused by(1) Damaged or deformed rotating band .

(2) Deformed or oversized rou nd .(3) Dirt, unbu rned prop ellant, or p ieces ofthe cartridge case liner accumulated in thelands and grooves near the chamber.

14. Immedia te Actiona. When the rifle fails to fire, the gu nner releases

pressure on the trigger and calls MISFIRE. Theloader rep eats MISFIRE, and w aits 1 minute.Then the loader unlocks and locks the breech andcalls UP. The gu nner attemp ts to fire.

b. Should the rifle still fail to fire, the gunnerreleases pressure on the trigger an d calls MIS-

FIRE. The load er rep eats MISFIRE, and againw aits 1 minute. Then th e loader opens the breechand unloads, being careful to catch the round asit is extracted. If the rifle has been fired con-tinu ously for a consid erable length of time be-fore a m isfire occurs, it becomes hot. Thismigh t cause the p ropellent charge to ignite bycookoff. If the rifle is h ot, cool with water b e-fore removin g the cartridge. If water is notavailable, all personnel will leave their posi-tions u ntil the rifle h as cooled (training only).

15. Redu ction of Stop pagesIf the rifle has misfired a second time and im-

mediate action procedures fail to reduce the stop-pag es, it is necessary to app ly add itional m easures.

a. After unloading the cartridge and placing itin a safe area, the gunner and loader should con-sider the following questions in determining thecause of the stoppage:

(1) What typ e of stoppage is this?(2) What causes this type of stoppage?(3) What parts have failed to function?

b. After determining the cause, corrective actionis taken.

15



25/71

Section IV. SPARE PARTS AND ACCESSORIES

16. Spare Parts disassembly, assembly, and maintenance of the rifle

Each using unit is provided with a set of spare are issued with it. Covers and tool rolls are also

par ts for the 90 mm rifle. These are issued as field issued with the rifle. Use these items for p re-

replacem ents for those parts m ost likely to becom e scribed purposes only. This equipm ent is listed in

w orn, broken, or otherw ise unserviceable. Requisi- TM 9-1015-223-12.

tion parts to keep the set complete. Components b. All new 90m m rifles are equ ipped w ith a

of the set ar e listed in TM 9101522312. sound suppressor ring. The purp ose of this soundsuppressor is to eliminate the telltale ring which is

17. Equ ipm ent heard when the weapon is hit by a solid object.a. Tools and ma terial necessary for au thorized

Section V. AMMUN ITION

18. General DescriptionAmmunition for the 90mm rifle is issued in

complete fixed cartridges. The term fixedmean s that the p rojectile and th e cartridge caseare crimp ed together. This insures correct aline-

men t of the pr ojectile and the cartrid ge case. Italso permits faster loading because the p rojectileand the cartridge case are loaded as one unit. Therear end of the cartridge case is made of frangiblematerial that is completely destroyed when fired.

19. Care, Hand ling, and PreservationComplete rounds are p acked individually in

moistu reproof fiber containers and sealed withtape. Two rou nd s in containers are packed in awooden box and weigh approximately 47 pounds.This packaging is designed to withstand normalfield use. Since moisture and heat adversely af-

fect ammunition, observe the following precau-tions:

a. Do not take the sealing tape off the fiber con-tainer until the amm unition is to be fired.

b. Protect the ammunition from high tempera-tures and from direct rays of the sun. Do notdisassemble any part of the round .

c. Return all unfired rounds to their originalcontainers and m ark them. Fire these round sfirst in subsequ ent firing.

d. Never handle dud s If a pr ojectile is firedand fails to explode, the fuze may be armed . Any

movement of the projectile may cause it to explode.In training areas, dud locations are marked andreported to the range officer for destruction.

20. Class ificationThere-are two authorized rounds for the 90mm

recoilless rifle, M67. These a re TP M371 and

16

HEAT M371E1. The target practice (TP) roundis not standard, but it is available for issue in cer-tain areas. It is ballistically identical to the highexplosive antitank (HEAT) round but containsonly a sm all spotting charge as th e p rojectile

filler.21. High Explosive, Ant itank , M371El

a. The high explosive, antitank round (fig. 15)utilizes a special fin-stabilized pro jectile w hich em -ploys the shaped-charge principle to defeat armor.It does not dep end u pon velocity at the mom ent ofimpact for its effect. It relies upon a concentra-tion of the effect of the explosive filler throughits shape. The conical shape of the filler concen-trates the force of the explosion into a hot jet thatblows its way throu gh the arm or. The shape of

the filler is maintained by a metal cone whichforms a slug w hen th e filler is explod ed. Thisslug or metal may or may not follow the explosive

jet through the armor. The complete cartridgeweighs approximately 9 pounds. The projec-tile weighs approximately 6 pounds, and has amuzzle velocity of approximately 700 feet persecond.

b. For maximum effect, the shaped filler mustbe at exactly the right d istance from the face ofthe arm or w hen it deton ates. This distance iscalled stand -off. Stand -off is provided by the

ogive, or nose spike on the nose of the projectile.c. The HEAT roun d is used p rimarily against

arm or. It can be used against second ary targetssuch as gun emp lacements and pillboxes w ith ex-cellent results. The warhead is capable of pene-trating the armor of any known tank.



26/71

22. Fuze, PIBD , M530a. A fuze is a device used with a pr ojectile to

explode it at the time an d und er the circumstancesrequired.

b. The M530 fuze is point-initiating, base det-onating with an inertially operated graze system.The fuse is armed by setback forces through a de-lay system. On impact, a piezoelectric crystal(lucky element) in the nose spike is crushed andgenerates an electric current th at is transmittedby w ire to the fuze. The graze system insures

deton ation regard less of the angle of imp act.The M530 fuze is assembled with a booster. Dueto its location in the p rojectile, the fu ze is notvisible in assembled rounds of ammunition.

23. Subcaliber Device

The su bcaliber d evice (fig. 16) will be locallyfabricated from drawings approved by USAMC.This device will permit realistic gunner training ata fraction of the coat necessary when serviceammu nition is used.

160-412 O-94-2

17



27/71

Section VI. MAINTENANCE AND INSPECTION

24. G en eral

a. Preventive m aintenance is the systematiccare, insp ection, and servicing of equipm ent tomaintain it in a serviceable condition, preventbreakdown, and insure maximum operationalreadiness. First echelon p reventive maintenanceis accomplished by the equ ipment operator.

b. The operators role in the p erforman ce ofpreventive maintenance service is

(1)

(2)

(3)

To perform service each day the equip-

ment is operated.To assist the organizational maintenancemechan ics in the performa nce of anyother scheduled, p eriodic services speci-fied by pertinent technical manuals.To assist the organizational maintenancemechanics in the lubrication of the equip-ment in accordance with the pertinentlubrication directives.

25. General Procedures for In spections andPreventive Maintenan ce

a. Inspections to see if items are in good condi-

tion, correctly assembled, secure, not excessivelyworn, not leaking, and adequately lubricated, applyto most items in preventive maintenance and in-spection procedures.

(1) Inspection for good condition is usuallyby external visual insp ection to determ ine

18

(2)

(3)

whether the weapon is damaged beyondsafe or serviceable limits.Inspection of a u nit to see if it is correctlyassembled is usually a visual inspection tosee if all parts are present and in theircorrect, relative position.Inspection of the weapon to determine ifit is secure is usually a visual inspectionor a check by hand or wrench for loose-ness. This type of inspection includesany brackets, lockwashers looknuts, and

locking w ires, as well as any connectingtubes or wires.

(4) In an inspection for excessively worncomponents of the weapon it should bedetermined whether parts of the weaponare worn beyond serviceable limits or toa point likely to resu lt in a failure if thepar t is not replaced before the next sched -uled inspection.

b. For any special cleaning and lubrication in-structions required for specific mechanisms or partssee the pertinent section in TM 8-1016-228-12.

General cleaning and lubrication instructions areas follows:

(1) Use drycleaning solvent or mineral spirits(paint thinn er) to clean grease or oil fromall metal parts, except th ose exposed topowder fouling during firing. This sol-



28/71

(2)

(3)

(4)

vent will not readily dissolve the corrosivesalts from powder and primer composi-tions.Use rifle bore cleaner to clean all arma-ment parts which have been exposed topowder fouling d uring firing. Aftercleaning a part with rifle bore cleaner it isnecessary that the part be w iped dry and

oiled.After all parts are cleaned, rinse and d rythem thoroughly. App ly preservativelubr icating (PL) (special) oil to all pol-ished metal surfaces, other than opticalequipment, to prevent rusting.When authorized to install new parts re-move any preservative materials such asrust-preventive compound or protectivegrease. Prepare parts as required, andfor those parts requ iring lubrication ap-ply the lubricant p rescribed in the tech-nical manual.

c. General pr ecautions in cleaning are as fol-lows:(1)

(2)

(3)

(4)

Drycleaning solvent and mineral spiritsshould not be used near an open flame.Fire extinguishers should be providedwhen these materials are used. Use onlyw ell-ventilated areas.These cleaners evaporate quickly andhave a drying effect on the skin. If usedwithout gloves, they may cause cracks inthe skin and , in the ease of some individ-uals, a mild irritation or inflamm ation.Avoid getting petroleum prod ucts, such

as d rycleaning solvent, m ineral spirits, orlubricants on rubber p arts as they w ill de-teriorate the rubber.The u se of diesel fuel oil, gasoline, or ben -zine (benzol) for cleaning is prohibited.

d. To prevent formation of damaging mildew,shake out and air the canvas cover for severalhours at frequent intervals. Have any loose grom-mets or rips in the canvas repaired without delay.Failure to make immediate repairs may allow aminor d efect to develop into m ajor d amage. Mil-dewed canvas is best cleaned with a dry brush. If

water is necessary to remove dirt it must not beused until mildew has been removed. If mildewis present, examine the fabric carefully for evi-dence of rotting or w eakening of fabric by stretch-ing and pulling.

26. Lub ricating In structionsa. Usual Conditions.

(1)

(2)

(3)

(4)

(5)

(6)

(7)

Firing handle. After firing, or every 7days, d isassemble and clean w ith clean-ing solvent; wipe d ry and lubricate withPL (special).

Monopod assembly. Daily and after fir-ing, wipe dry and coat threaded p ortion

with a light film of PL (special).Front bracket assembly. Before firing,wipe d ry and lightly lubricate with PL(special). After firing, or every 7 days,clean w ith cleaning solvent, wipe dry andlightly lubricate with PL (special).Cable assembly. Before firing remove,wipe d ry and lightly lubricate with PL(special ). After firing, or every 7 days,remove, clean, wipe dry, an d lightly lubri-cate with PL (special).

Breech and hinge mechanism group. Be-fore firing, wipe dry and lubricate tooth

on inn er hinge p ortion of the breechblockand all threaded portions of the breech-block with Aircraft Instrument GreaseMIL-L-46000. Apply a light coat of PL(special) to all other surfaces. Wipe ex-ternal surfaces dry before firing. Afterfiring, and on 3 consecutive days there-after, clean with rifle bore cleaner. Afterthe fourth cleaning, dry and lubricate asabove. When the weapon is not fired, dis-assemble, clean with cleaning solvent;wipe d ry and relubricate every 7 days.

Rear mounting bracket group. Before

firing, wipe d ry all parts and lightly lub-ricate with PL (special). After firing, orevery 7 days, clean with cleaning solvent;wipe dry all parts and lightly lubricatewith PL (special).Tube. After firing and on 3 consecu-tive days thereafter, clean bore with borecleaner. After the fourth cleaning, dryand lubricate bore with PL (special).When weapon is not fired, clean the tube,wipe d ry, and reoil every 7 days. Wipedry before firing.

b. Unusual Conditions. Reduce or increase lu-brication intervals as required to compensate forabnormal operation and extreme conditions, suchas high and low temperatures, prolonged periodsof high rate operation , continued operation insand or du st, or exposure to moisture. Any one

19



29/71

of the above may quickly destroy the protectivequalities of the lubricant. Lubrication intervalsmay be extended du ring inactive periods.

(1)

(2)

(3)

Extreme cold weather lubrication. Ap -ply a light coat of low temperature lubri-cating oil to the rifle, and move the func-tioning parts frequently during periodsof low temperature to insure p roper func-

tioning. In extreme cold w eather areas,the weapon mu st be wiped dry after lu-brication so that only a minimum amou ntof lubricant remains.Extreme hot weather lubrication. Spe-cial lubricants will ordinarily not be re-quired at extremely high temperaturesbecause the lubricants prescribed for theweapon provide adequate protection.However, more frequent servicing is nec-essary because heat dissipates the lubri-cants.Lubrication for humid and salt air con-

air tend to contaminate the lubricant,necessitating frequent servicing.

(4)Lubrication after operation under dustyor sandy conditions. Thoroughly cleanthe weapon and lubricate as prescribed ina above.

27. Recordin g Procedu res

The equipment record system provides for re-cording repairs required and accomplished onspecific items of equipment. This will include,but is not limited to, adjusting, cleaning, and re-placing. Deficiencies discovered before, during,or after operation that cannot be corrected by theoperator w ill be entered on DA Form 2404, Equip -ment Inspection and Maintenance Worksheet.Deficiencies imm ediately corrected by th e op eratorare not recorded , except wh en such correct ions aremade by replacing parts, or which constitute re-pa irs above first echelon. Such r epairs w ill be

ditions. High humidity, moisture, or salt recorded as organizational maintenan ce.

Section VII. DECONTAMINATION PROCEDURES

28. Preparation and Testing

Oil rifles completely if chemical, biological, orradiological attacks are anticipated. Also oilaccessories, except ammunition. Keep ammuni-tion waxed wh en p ossible. Test for contam ina-tion, using detector paper for liquids or detectorcrayon for vapors. If equipment is not contam-inated, clean and prepare it for use.

29. DecontaminationIf equipment is contaminated, decontaminating

personnel should use a complete suit of protectiveclothing (perm eable or impermeable), includ ingimpermeable gloves and protective mask.

a. Equipment contaminated with chemicalsother than th e blister agen t or G-series agents, isdecontaminated by airing. For faster decontam-ination and to protect against corrosion, clean therifle and accessories with rifle bore cleaner, dena-tured alcohol, or soap and water.

b.Equipment contaminated by blister agents isdecontaminated as follows:

(1)(2)(3)

(4)

(5)

(6)

c. In

Remove all dirt, du st, grease, and oil.Expose all p arts to air.Decontaminate all metal surfaces exceptthe bore with agent, decontaminating,noncorrosive (DANC) (FM 21-40).Hot soapy w ater is also an effectivecleaner.Protective ointment, M5, can be used for

emergency decontamination (FM 21-40).Test with detector kit to determine ifdecontamination is comp lete. If com -plete, clean, dry , oil, and prep are riflefor use.Burn, or preferably bury, all rags orwiping materials.

Note. Caution should be used to protect menagainst vapors created by burning.

general, these actions are app licable toequipment contaminated by biological or radio-logical attack. Detailed information on decon-

tam ination is contained in FM 21-40 and TM3-220.

20



30/71

Section VIII. DESTRUCTION IN EVENT OF IMMINENT CAPTURE

30. D estruction To Preven t Enem y Use

a. General. Destruction of material is accom-plished on au thority delegated by d ivision orhigher commander. This is usu ally a matter ofstanding operating p rocedures. It is ordered onlyafter all measures to save the equ ipment have been

taken.b. Principles of Destruction.

(1)

(2)

(3)

(4)

Methods of destruction are adequate, uni-form, and easily followed in the field.Destruction is as comp lete as possiblew ithin the lim itations of time, equipm ent,and p ersonnel. In any event, the mostimportant parts of the weapon are de-stroyed or evacuated. The same essentialparts are destroyed or evacuated on alllike un its to prevent the enem y from con-structing one complete rifle from several

damaged ones.Crews are trained in p rescribed methodsof destruction.Certain methods of destruction requirespecial tools and equipm ent such as TNTor incendiary grenades. Issue of suchspecial equipment and its use are com-mand decisions and depend on the tacticalsituation.

c. Destruction of the Rifle.(1)Method No. 1demolition materials.

When p lanning for simultaneous detona-tion, prepare th e following d emolitioncharge-s using TNT blocks or an equiv-alent to make u p the required charge.

(a) One-pound charge. Insert the chargein the m uzzle of the rifle to a distanceof about 1 foot. Plug the bore to adistance of about 8 inches with earth,stone, or similar material, being carefulnot to damage the detonating cord.

(b) Two-pound charge. Insert the chargeinto the chamber. Pass the detonatingcord out of the chamber through oneof the vents in the breechblock. Plug

the vents with any available materialsuch as rags or mu d, being careful notto dam age the detonating cord.

(c) Connect the tw o charges for sim ul-taneous detonation with detonatingcord. For comp lete details on the use

(2)

of demolition materials and method ofpriming and detonating demolitioncharges refer to FM 525.

Method No. 2burning with incendiarygrenades. Destruction of essential partsfollowed by burning in an intense fire will

usually render the rifle and related mate-rial useless. Since the rifle and relatedmaterial are made almost entirely ofm etal, effective destru ction by th is meansrequires larger amounts of combustiblematerial than m ay be available. How-ever, the use of incendiary grenades willrender the rifle useless.

(a)

(b)

(c)

Insert two incend iary grenades, end-to-end , midway in the tube. Place a thirdincendiary grenade, fitted with a timeblasting fuze, adjacent to the grenad esin the tube.

Note. Time blasting fuze burns at a rateof 1 foot in approximately 40 seconds; testbefore using.

With the breech open, place two in-cendiary grenades in the chamber.Place a third incendiary grenade, fittedwith time blasting fuze, adjacent to thegrenades in the chamber.Ignite the fuzed grenad e. The timeblasting fuze may be ignited by a blast-ing fuze igniter or a m atch. The metal

from the grenad es will fuze with thetube an d w ill also weld the breechblockand vent bushing.

Note. When fitting incendiary grenad eswith time blasting fuzes, the fuzes shouldbe of sufficient length so personnel may safelyleave the immediate area before the grenadesare detonated.

(3)

(4)

Method No. 3by gun fire.From anadjacent r ifle or gu n, tire on th e rifle andrelated material to be d estroyed. Al-though one well-placed direct hit may

render the rifle and related material tem-porarily useless, several hits may be re-quired for complete destruction.Optical instruments. Remove the d irectfire sight. It is relatively lightweightand easy to carry, and is costly and diffi-

21



31/71

cult to rep lace. It should be evacuated if t rench or depression. Place f lamm able materia lspossible. When evacuation is impractical such aS paper, rags, and wood around and on thethen smash the sight and m ount. pile. Pour gasoline and oil over the combustible

materials and over the entire ammu nition pile.31. Destruction of Am mu nition Ignite by means of an incendiary grenad e fired

Ammunition is most effectively destroyed by from a safe distance, a burst from a flamethrower,burn ing. To accomplish this, stack rou nd s (either a combu stible train of suitable length, or other ap -pa cked or un packed ) in piles, pr eferably in a propriate means. Take cover immediately.

22



32/71

CHAPTER 3

PREPARATORY MARKSMANSHIP

32.

a.

Section I.

Introduction

Preparatory marksmanship training teachesessential skills and develops fixed and correcthabits of marksmanship before range practice be-gins. Thorough instruction and carefully super-vised practice in the preparatory phase saves timeand amm unition du ring range firing and develops

habits and procedures necessary for well-trainedgun crews.b. Marksman ship and firing explained h erein

cover both subcaliber and field firing.

GENERAL

33. Sequen ce of Training

Preparatory marksmanship is divided into stepsnormally taught in the following sequence:

a. Sighting and aiming.b. Positions.c. Adjustment of tire.d. Trigger mannipulation.

e. Tracking.f. Examination.

Section II. INDIVIDUAL DUTIES

34. Duties of Sq uad Leader

The weapon s squad leader is in direct comm andof the crew and is responsible for its equipment.He observes, adjusts, controls, and supervises thecond uct of fire of the 90mm rifle. He emp loys thesquad according to orders of the platoon leader andis responsible for prop erly concealing th e w eapon.He keeps the p latoon leader informed of the statusof the amm unition supply and supervises hiscrews ammu nition resup ply.

35. Organ ization an d Equ ipm ent for CrewDrill

IndividualCrew members weapon Individual load

No. 1: Gunner ------- Pistol ----- 90mm rifle withtelescope sight.

No. 2: Assistant Pistol ----- Ammu nition carry-

gunner (loader am- ing strap, tools,mu nition bearer). spare parts,cleaning ma-terial, and 3rounds of 90mmammunition.

IndividualCrew members weapon Individual load

No. 3: Ammun ition Rifle ------ Ammunition carry-bearer*. ing strap and 4

round s of 90mmammun ition. 3rounds in strapand 1 in hands.

*Note. See current TOE. The third crew m ember, wh ile notcurrently au thorized, is considered necessary for efficient op era-tions. In the absence of an individual to perform the dutiesassigned to N o. 3, ammu nition bearer, No. 2, the loader, will beresponsible for these duties too.

36. Du ties of Crew Mem bers

a. No. 1, the gunner, lays and fires the 90mmrifle and is the crew leader. He makes necessaryfire adjustments as called for by the squad leader.He is responsible for the m aintenan ce of the rifle

and coordinates his actions with No. 2.b. No. 2, the loader, is responsible for loadingthe 90mm rifle and acts as gunner shou ld thenecessity arise. He secures am mu nition and checksclearance of the backblast area p rior to firing. He

23



33/71

assists in the maintenance of the rifle and coordi- for securing ammunition. While not engaged innates his movem ents and d uties with No. 1. ammunition resupply, he provides security for the

c. No. 3, the ammunition bearer, is responsible rifle position.

Section III. CREW DRILL

37. Gen eral broken, and sight is clean and tight in the

a. Purpose. The objective of crew drill is totrain the individu al as a member of the crew toplace the rifle in and out of action with p recisionand speed.

b. Training. The attainmen t of precision is thefirst step in develop ing an expert crew and is ac-quired by strict adherence to the p rescribed pro-cedure. Only after the desired ind ividu al preci-sion has been attained are the next phasesteam-work and speedundertaken.

c. Teamwork. Teamw ork is assured by rotationof duties du ring dr ill so each crew m ember, by

practice, becomes fam iliar w ith the d uties of everyother member. Continuity of action is made cer-tain by this ph ase of training.

d. Speed. Practice for speed is instituted as thelast phase of instruction in crew drill. Care mustbe taken du ring this phase to insure that p recisionand teamwork are not sacrificed for speed.

38. Formin g for Crew D rill

At the command FORM FOR CREW DRILL,mem bers of the crew , except the squ ad leader, fallin at attention in a colum n w ith five paces betweenmen and face the squad leader. To assign p osi-tions for crew drill, the squad leader comm andsCOUNT OFF. On that command, the crew callsoff from front to rear starting w ith N o. 1 (thegunner).

39. Posting the Sq uad

At the comman d POST, all crew mem bers moveforward at double time to prone positions directlybehind their equipment which is laid out in order.

40. Examine Equipment Before Drill

At the command EXAMINE EQUIPMENTBEFORE DRILL (while crew is in the proneposition), crew members examine equipment asfollow s :

a. No. 1, Gunner.(1) Checks to see that sight and sight mount

are workable, cross level vial is not

bracket.(2) Checks the operation of the bipod and the

monopod.(3) Checks the chamber and the functioning

of the lockring.(4) Checks the firing m echanism and the

safety lever for proper functioning.b. No. 2, Loader.

(1) Checks his ammunition for amount andprop er seal of the containers.

(2) Checks tools, spare par ts, and cleaningmaterial.

c. No. 3, A mmunition Bearer.

(1) Checks his ammun ition for amou nt.(2) Checks the seals of ammu nition contain-

ers.

41. Reports

When all equipment is checked, the followingrepor ts are given (incorrect items are repor ted-when a deficiency exists):

a. No. 3, the ammunition bearer, reports AM-MUNITION CORRECT.

b. No. 2, loader, reports AMMUNITION,TOOLS, SPARE PARTS, AND CLEANING

MATERIAL CORRECT.c. No. 1, gunner reports ALL CORRECT.

42. Placing Rifle Into ActionTo place the w eapon into action, the squad

leader comm and s ACTION, and designates bypointing th e direction of fire and the genera l areaof the rifle position. He p laces himself on theflank in a position from which he can observe andcontrol the fire. At the comm and ACTION, thecrew mov es rapidly to the position ind icated.Where necessary, the squad leader may also in-dicate the type of position to be taken by N o. 1

(prone, sitting).a. No. 1 selects the exact spot and assumes thefiring p osition from w hich he can best accomp lishhis m ission. H e lays the rifle on th e target, placeshis right hand on the trigger grip, and aw aits areport th at the r ifle is ready to fire. H e fires as d i-rected by the squad leader.

24



34/71

b. No. 2 assists No. 1 in placing the rifle in ac-tion by holding the rifle while the gunner placeshis body in position or while the gunner adjuststhe bipod. He opens the breech. He inserts thecartridge into the chamber and seats it firmly. Hethen closes and locks the breech and inspects thebackblast area to see that it is clear. If it is clear,he rotates the safety arm to the fire position, taps

the gunner, and calls UP to ind icate that the rifleis ready to fire.c. No. 3 takes a position on the right flank

from which he can readily bring up ammunitionand from wh ich he can provid e security for theposition.

d. After firing, the loader opens the breech withhis right hand and ejects the expended cartridgecase.

43. Takin g the Rifle O ut of ActionThe squad leader command s OUT OF ACTION .

Upon this comm and , the loader clears the 90mm

rifle, calls CLEAR, and closes the breech. No. 2takes th e rifle from No. 1. (When th e rifle is firedfrom the p rone p osition, No. 2 holds the r ifle wh ileNo. 1 adjusts the bipod for the shoulder carry.)No. 2 now secures his amm unition and tools. No. 3secures his ammunition. The squad leader indi-cates the line of march by facing in that direction.The crew places itself in colum n behind the gu n-ner, and moves on command from the squad leader.

44. Service of th e Piecea. Unloading 90mm Rifle (fig. 17). To open the

breech, the loader grasps the lockring handle withhis right hand (over the chamber), lifts up on the

45.a.

lockring h and le (rotating the breechblock ap proxi-m ately 45

0clockwise ), and then rota tes the breech-

block vigorously to the rear.b. Loading 90mm Rifle (fig. 18). To load the

90mm rifle, the loader inserts a cartridge into thechamber and completely chambers it by sharplypushing the cartridge all the way forward. Toclose and lock the breech, he grasps th e lockring

hand le with his right hand , moves the breechblockforward un til it is seated in the breech, and rotatesthe lockring coun terclockwise un til it is fullylocked. Up on locking the breech, he inspects thebackblast area to see that the area is clear. Ifthe area is clear, he moves the safety arm to thefire position F(fig. 19), taps the gunner on theshoulder, and calls UP to indicate to the gunnerthat the r ifle is ready to fire. Figu re 19 Showsthe safety arm in the safe position.

c. Firing. To fire the 90mm rifle, the gu nn erdep resses the trigger grip safety and then thetrigger.

d. Clearing the Rifle. The loader opens thebreech and checks the chamber to see that the pieceis un loaded . He calls 90 CLEAR.

e. Safety. The loaders safety enables the gu n-ner to move w ith a cartridge in the chamber ofthe rifle without danger of accidental discharge.The loader, after loading a cartridge, closes thebreech w ithout rotating th e safety arm to the fireposition. In this position, the firing m echanism ismechanically blocked so it cannot be fired. Toprepare the 90mm rifle for firing, the loader hasonly to check the backblast area, rotate the safetyarm to the fire position, tap the gunner, and callUP.

Section IV. GUNN ER AND ASSISTANT

Sighting and AimingAiming for Range.(1)

(2)

Du ring t he first exercise, a stationary

GUNNER TRAINING

reticle; for example, 425 meters, 525meters. A trained gunner, acting ascoach, should check each sight picturewh en in the prone p osition.1,000-inch A rifle target (or some other

appropriate target) is used as an aiming b. Aiming With Leads.

point. To aim for range, select the cor- (1)

rect segment of the vertical line of the

reticle and place it on the center of thevisible mass of the target.Find the correct sight p icture for each (2)successive 50 meters of range on th e reti-cle. Then progress to sight pictures thatrequire interpolation of range on the

The reticle is provided with a horizontalscale, graduated in 5-mil (one lead)

units, which furnishes a means of apply-ing leads (para 5).To aim w ith leads, keep th e vertical rangeline ah ead of the center of mass of thetarget. To hit a target w hich has lateralmovement with respect to the direction

25



35/71

26



36/71

(3)

of fire, point the axis of the bore a headof the target. Use leads for firing onmoving targets. No leads are used fortargets moving d irectly toward or awayfrom the gu n position. Aim at the centerof visible m ass.Exercises are condu cted w hich requiresetting announced leads on a subcalibertarget (1,000-inch) or some other app ro-priate aiming point. The target re-

mains stationary, but it is assumed to beat any range from 0 to 600 meters andmov ing from right or left at speed s re-quiring variation in the num ber of leads.

c. Aiming for Range With Leads. Range andleads are combined on the sight reticle by a seriesof segmented horizontal lines.

(1)

(2)

Lead lines extend right and left of thevertical rang e line. Interp olate rangesbetween the 50-meter intervals etched onthe sight reticle. Select appropriaterange (this will be imaginary if it is in-terpolated) and lead on the reticle andproject them to the point of intersection.Place this point on the center of mass ofthe target.The length of one space or of one line ofthe horizont al line is equal to one lead.For instance, the point at the end of the

(3)

first space represents one lead; the pointat the end of the second line, four leads(two spaces and two lines). Count off onthis line, to the left or righ t of the verticalrange line, the nu mber of leads needed.Lay the rifle on the target a t several dif-

(4)

ferent ranges and leads. The target re-mains stationary, but an assumed range,the direction, and the nu mber of leads arespecified in each case. The coach checks

each sight picture wh en in the p rone posi-tion. Range and leads requiring inter-polation are included.At least one period of this training is de-voted to th e use of the illum inated r eticle.This accustoms p ersonnel to aiming d ur-ing p eriods of limited v isibility.

46. Position Exercises

Position exercises teach the positions used by thegunner and loader when firing from both groundor shoulder moun t at stationary and moving

targets. Aiming and servicing the weap on can beincluded in position exercises. Each crew memberis taught to fire the rifle from the prone, sitting,kneeling, standing, and foxhole supported posi-tions. By giving close attention to details duringall position exercieas, the crew should be able to

27



37/71

assume p roper p ositions au tomatically. For serv-ice of the piece, see paragraph 44.

a. General Characteristics of Positions. Thefollowing characteristics apply to all firing posi-tions:

(1)

(2)

(3)

Remain steady in each p osition w ith aminimu m of muscular effort.In each position, there is some p oint atwhich the rifle aims naturally and withouteffort. If this point is not the center of

the target, shift the body to bring th e rifleinto the correct alinemen t.In any firing position except the prone,the gunn er may be steadied by the loader.

b. Prone Position.(1) Gunner. Lie on the stomach to the left of

28

(2)

the rifle and at an angle of approximately90 to th e p iece (fig. 20). With th e lefthand , grasp the monopod. Place theright hand on the trigger grips by reach-ing under the tube. To adjust for eleva-tion, screw the monopod up or down. Totrack a moving target, raise up on themonopod track right or left, allowing therifle to pivot on the bipod legs.Loader. When loading, assume a proneposition (fig. 21) opposite the gunnersright shoulder, perpend icular to theweapon, and facing slightly to the rear.The position m ust be close enough to thegunner to be able to communicate withhim and, at the same time, load the rifle.Move about to conform w ith the gunn ers



38/71

movements, to avoid the backblast, and toload th e rifle.

c. Sitting Position.(1) Gunner. There are two sitting p ositions:

One for stationary targets and one formoving targets.(a) To assume th e sitting p osition for mov-

ing targets (fig. 22), sit facing the tar-get with legs crossed an d feet draw nup und er the legs so the outer part ofthe calf of one leg rests on th e inside ofthe oth er foot. Bend slightly forwardfrom the hips, and hold the backstraight. Grasp the monopod with theleft hand . Grasp the trigger hand le as-sembly with the right hand , and holdthe right elbow at shoulder level to form

a p ocket for the bipod shou lder rest.(b) The sitting p osition for the stationa ry

targ et (fig. 23) is sim ilar to th e op en

leg sitting position for firing the M14rifle. In assuming this position, legsare extended and spread a comfortabledistance apart. Brace the legs by dig-

ging heels into the grou nd , toes point-ing in, and rest the elbows on th e insideof the knees.

(2)Loader. The loader takes a kneelingposition opposite the gunners rightshoulder and faces to the rear of therifle (figs. 24, 25). He places one or bothknees on the grou nd . If he places oneknee on the groun d, it mu st be the leftknee w hich is nearer to the breech. Heplaces himself close enough to the gu nnerto comm unicate with him and at the sametime load the w eapon. As in the other

position, the loader moves about whiletracking to conform with the movementsof the gunn er, and to load the w eapon.

29



39/71

30



40/71

d. Kneeling Position.(1) Gunner. There are two kn eeling p osi-

tions, one for stationary targets and onefor moving targets.

(a)

(b)

To assume the kneeling position for

m oving tar gets (fig. 26), the gu nn erkneels on his right knee with the up perpart of the right leg vertical. His but-tock does not rest on his right heel. Hepoints his leg toward the target withhis left foot at a right angle to theknee and opposite his right knee. Hisleft leg forms a right angle to thegroun d. Holding his body erect, heplaces his left elbow under the piece.He grasps the monop od w ith the lefthand, grasping the trigger grips withhis r ight hand. He holds his rightelbow high, forming a p ocket for thebipod shoulder rest.The kneeling position for the station-ary target (fig. 27) is similar to thekneeling p osition for firing th e M14rifle. The gun ner kn eels on his right

knee at a 90 angle w ith the line of aim,sits so the center of his right bu ttockrests directly on his right h eel, andshifts his weight forward so his heelinclines in the direction of the target.

When viewed from the front, his leftleg is vertical; however, it need not ap-pear vertical when v iewed from theside. The gunner m ay prefer to drawhis left foot back, relaxing h is bodyweight forward so a solid contact ismad e between his calf and thigh. Hepoints his left foot in the d irectionw hich gives him the m ost comfort, restshis left upp er arm or left elbow on hisleft knee, and places his left and righthands as prescribed for the sitting and

standing positions. He raises his rightelbow to the height of (or slightlyabove) his shoulder, forming a pocketfor the bipod shoulder rest.

(2)Loader. The loader takes the same posi-tion as explained in c (2) above.

31



41/71

e. Standing Position.(1) Gunner. The standing position is similar

to the stand ing position for firing the M 14rifle (fig. 28). To assu m e the stan d ingposition, the gunn er stand s half-faced tothe right w ith his feet a comfortable dis-tance apart and his body erect and wellbalanced. H e grasps the monopod withthe left hand and the trigger grips withthe right hand. He raises his right elbowto the height of (or slightly above) hisshoulder, forming a pocket for the bipodshoulder rest. To traverse in th is po-sition, he mov es his body from the an klesup .

(2)Loader. The loader takes a stand ing

position opposite the gunners rightshou lder. The loader faces the rear ofthe rifle, close enou gh to th e gun ner tocommunicate with him and, at the sametime; load the weapon. As in the otherpositions, the loader m oves about while

32

tracking to conform with the movementsof the gunner, and to load the w eapon.The loader may assist in steadying thegunner by grasping him arou nd the chestor waist (fig. 29).

f. Foxhole Supported Position.(1)

(2)

Gunner. The foxhole supp orted p ositionis similar to the standing position exceptthat the gu nner faces directly to the front,and the monopod rests on the ground(fig. 30).

Loader. The loader faces the rear of therifle and adjusts his position as the gunnertracks a target or otherwise moves therifle. The loader must pay particular at-tention to the backblast area w hile in this

position. It is extremely imp ortantthat th e breech of the rifle clears therear edge or parapet of the foxhole.It may be necessary to u se sandbags infront and/ or in the bottom of the foxholeto obtain the required breech clearance.



42/71

47. Adjustm ent of Firea. General. After crew m emb ers are fam iliar

with the u se of the sight and have had trainingin techniques of fire, they are read y for simpleexercises in adjustment of fire. Each should prac-

tice the m ethod d escribed below.b. Burst-On-Target.(1) Use a 1,000-inch target and announce a

range to use for the initial lay of theweap on. Show th e burst of a round onthe face of the target, using a burst mark-er on a pointer. Location of the burstshould be over or short.

(2) Have students and coaches mentally notethe location of the burst on the sight reti-cle. Remove th e burst m arker from theface of the target and have stud ents movethe remembered burst to the center ofmass of the target.

48. Breath in g

a. Accurate fire requires proper breathing. Ifthe gunners chest and back are moving, he does

160-412 O-94-3

not keep his eye in the same position with refer-ence to the sight, and the sight picture seems tomove. Constant practice in proper breathing isnecessary until the gunner automatically holds hisbreath correctly when firing the weapon.

b. To preven t breathing from interfering withhis sight picture, the gu nner initially takes abreath of air, lets out a portion of it, then holdsthe remainder naturally. If the gun ner d oes notfire within a reasonable length of time (8 or 9 sec-onds), he does not attempt to fire, but relaxes,takes several breaths, and again attempts to fire.Constant practice is necessary to control breathingwithout discomfort.

c. To check the gunner for proper breathing,w atch h is back. If it rises and falls as he aim s,he is not breathing prop erly. If the rifle is being

fired from the shoulder an d the m uzzle of the rifleseesaws, the gunner is breathing improperly.

49. Trigger Man ipu lationa. One of the most importan t elemen ts of marks-

manship training is manipulation. Everything

33



43/71

about the position and aiming may be perfect, butunless the trigger is man ipulated p roperly, theweap on w ill be pu lled to th e left or right. Al-though jerking the trigger may appear to disturbthe sight only slightly, the slightest movemen tspoils a good shot. A more extensive movement,made in anticipation of firing, is called flinching.It occurs only if the gunner know s the exact mo-ment w hen th e rifle will fire. The gunner sh ouldmanipu late the trigger so he does not know theexact moment the 90mm rifle will fire.

b. The gunner takes a breath, expels part of it,and locks in the rest with h is throat mu scles. Hethen alines the sight on the target and depressesthe trigger safety w ith the crotch of the hand be-tween the thu mb an d index finger. He exerts aslight initial pressure on the trigger, then continuesto squeeze with a steady, smooth pressure to the

rem. He holds the correct sight p icture, squeezesthe trigger, and continues to h old the trigger brief-ly after the rou nd is fired. If this procedu re isfollowed, each round fired comes as a surprise tothe gunner, thereby eliminating flinching. Con-

34

stant practice of trigger manipulation under theobservation and sup ervision of a good coach great-ly improves accuracy.

c. Important p oints about trigger m anipulation:(1)

(2)

(3)(4)

(5)

(6)

Depress the trigger safety before puttingany initial pressure on the trigger.App ly smooth, steady p ressure on th etrigger straight to the rear.Do not wait too long to fire a round.Concentrate on the sight picture ratherthan the right hand.Every shot mu st come as a surp rise to thegunner.Do not snap shoot because it will exag-gerate flinching.

50. Trackin g

When proficiency is obtained in sighting a nd

aiming, positions and trigger manipu lation train-ing in tracking a moving target begins. Thistraining progresses from simple tracking to m ov-ing objects at 25 meters to more difficult exercisesof tracking moving targets under field conditions.



44/71

35



45/71

36



46/71

Any exped ient can be utilized in the preliminaryphases. When tracking under field conditions,combat vehicles such as tanks or trucks are used.

51. Examina tion

a. General. Before comm encing ran ge firing,examine personnel to determine whether they haveachieved the desired standard of proficiency. Cor-rect deficiencies, as determined by the examina-tion, with add itional training. Use either w ritten,oral, or p roficiency-type examina tion. The pr o-ficiency-type examination should be used when-ever possible.

b. Written Examination. Use the objective-type written examination and include questionsconcerning all the steps of marksmanship.

c. Oral Examination. An oral examination,conducted as a question and answer period, con-sists of objective-type questions. These questionsshould be broad in scope, requiring som e explana-tion and discussion by the soldier.

d. Proficiency Examination. Conduct a pro-ficiency examination using the county fair

method (AR 320-5). Setup various stations withspecific requirem ents at each station.

(1)

(2)

(3)

(4)

Sighting and aiming station. At thisstation, an assistant instructor givesthe students various sight picture situa-tions and then checks each sight picturefor accuracy. He also gives the studentsa problem that requires a change fromthe initial sight picture to simulate ad-justing fire and the receipt of a su bse-quent fire command .Position station. An assistant instructor

requires the students to assume the var-ious positions acceptable for the gunnerand loader for firing the 90mm rifle.Safety station. An assistant instructorrequires the student to explain the me-chanical safety features of the weap onand the range and safety regulations(90mm backblast).Other stations. Stations for examiningtrigger manipulation and breathing mayalso be conducted. Any other stationsdesired may be used, but definite require-ments m ust be established at each station.

37



47/71

Section V. RANG E PROCEDURES AN D SAFETY

52. Training Procedure

a. During all instru ctional firing, emp hasisshould be p laced on rap id adjustment of fire and atarget hit with the second round as a minimumgoal.

b. During the initial phases of instruction fir-

ing, the officer conducting the firing may, at hisdiscretion, reduce the speed of the target and thenumber of cartridges fired in each run. The ob-ject of this is to increase the m ans confiden ce andplace emphasis on manipulation and accuracy.

c. All exercises are fired in the order listed inthe tables (chap. 4) and are controlled by appro-priate fire comm and s.

d. Moving target firing is preceded by one ormore dry runs during instruct ion firing.

e. All 90mm rifles are inspected by a qu alifiedindividual before and a fter each firing to ma kesure th e rifle has the correct ad justm ent, is cleanand free from excessive wear, and operatesproperly.

f. Instructor insure that no part of any per-sons body is behind the br eech of the rifle w hen alive cartridge is in the 90mm chamber. The load-ers, in p articular, are cautioned to keep their arm sfrom moving behind the breech during firing.

g. Extreme caution must be exercised in open-ing th e breech of any rifle wh ich fails to fire.Danger of accidents is greatest at th is time. Afterthe rifle is cleared, it will be inspected by a quali-fied ind ividual to d etermine the cause of the fail-

ure.DO

not use a rifle that has failed to fire until ithas been examined and approved by a qualifiedindividual.

53. Off icer in Ch arge

The officer in chargea. Assigns, coordinates,

ing line.b. Organizes the range.

and supervises the fir-

C. Determines which position is to be used infiring each table.

d. Issues fire commands and general instruc-tions to th e firing line.

e. Enforces safety precautions prescribed in AR385-63.

f. Decides whether an alibi run should be au-thorized in the event of breakage or stopp age inthe range apparatus.

38

54. Scoring Personnel

Scoring personnel detailed to supervise recordfiring are normally from organizations other thanthe one firing. Before record firing, they famil-iarize themselves thoroughly with firing proce-dures and the following specific duties:

a. Issue scorecards.b. Check scoring spaces.c. Inspect each target before firing to insu re

that it contains no unpasted shot holes.d. Count number of rounds of ammunition fired

by the gunner for each exercise.e. See that firing is conducted in accordance

with p rescribed procedure.f. Decide whether misfires and malfunctions of

the rifle are the fau lt of the firer.g. Score the targets on each exercise fired and

record the score.

55. CoachesDuring all instruction firing, a coach is at each

rifle to instruct and assist the gunn er; however, nocoach is p resent at the rifle for the record firing.The loader is present at all firings. The coaches

a. Require each gunner and loader to observe allsafety precautions and see that they comply withinstructions pertaining to the service of theweapon.

b. Sup ervise the work at the weapon and m akesure the command s are executed p roperly. Rep-eat orders and instructions when necessary to in-sure correct understanding and timely execution.

c. Report all misfires, malfunctions, or d iscrep-ancies to the officer conducting the firing.

d. Critique the firing.

56. Loade rThe primary duty of the loader is to service the

90mm rifle during all firing exercises. Duringrecord firing, the loader does not coach or instructthe gunner in any way. He

a. Loads the 90mm rifle in accordance with thecommands of the officer conducting the firing.

b. Taps the gunn er and reports UP when theweap on is loaded and he is clear of the breech, andthe backblast area is clear.

c. Signals READY to the officer conducting thefiring.

d. Repeats all orders to unload, cease fire, andclear the weapon .



48/71

e. Announces to the gunner the number ofroun ds to be fired in each exercise, and sees that th ecorrect number of rounds are available.

57. O rganizationa. See figure 31 for organization of the firing

line.b. See paragrap hs 53 throu gh 56 for duties of

personnel.

c. No personnel except those actually requiredon the firing line are allowed to enter the fenced orroped-off inclosure at any time.

d. Before firing, each 90mm rifle is checked by aqualified ind ividua l to insure that it is in firingcondition.

58. In structionFiringa. Before firing, the officer in charge of firing

gives a description of the range and annou ncesspecific instru ctions p ertaining to firing p rocedu re.

b. Rifles are nu mb ered from right to left.c. The coach, loader, and gunner take positions

at the r ifle. The gun ner tests the firing m echa-nism, bipod legs, and m onopod ; the loader obtainsnecessary ammunition.

d. When all rifles are prep ared for firing andthe observance of safety regulations is checked,the officer conducting firing gives the fire comman d.

e. At the comp letion of an exercise the officerconducting the firing commands CEASE FIR-ING. The loader rapidly unloads the rifle andma kes certain that all personn el are stand ing clearof the rifle, and then raises his arm to signal theofficer in charge that the position is clear.

59. Stationary an d Mov ing Target Exercisesa. An examp le of the sequence of the fire com-

man d for stationary target firing is as follows:FIRE MISSION, FRONT, TARGET,HUN DRED. When all rifle positions have sig-naled READY, the officer conducting the firingcommands FIRE. Each gunner fires as directeduntil his ammu nition is expend ed or u ntil the com-ma nd CEASE FIRING is given.

b. An example of the sequence of a fire commandfor mov ing ta rget firing is as follows: LAY ONAIMING STAKE. When all rifles are laid onthe aiming stake, the fire command continues asfollows: MOVING TARGET, LEFT FRONT,TANK, _______ HUNDRED, TWO LEADS,FIRE. The loader loads on the am mu nition ele-ment of the fire comm and . When the target com-pletes its run, the command CEASE FIRING isgiven.

60. Record Firing

The same procedure as that prescribed for in-struction firing is employed for record firing, ex-cept as noted below:

a. Each man completes the prescribed instruc-tion firing for the course sp ecified before recordfiring.

b. Unless the allotted time for firing is limited,record firing does not occur the same d ay that anyportion of instruction firing occurs.

c. Before firing any exercise for record, the gun-ner is given a reasonable length of time to check thecondition of the w eapon, sights, and am mu nition.

39



49/71

d. The gunner boresightsweap on before record firing.

or zeros his own

e. The target speed and the allotted time are d es-ignated to each gunner before firing.

f. In record firing, when a misfire, stopp age, ormalfunction occurs, the gunner or loader holds uphis hand and calls MISFIRE. Thereafter neitherthe loader nor gunner touches the rifle until thescorer examines it.

g. If a misfire, stoppage, or m alfunction occursthrough no fault of the gunner, the score is dis-regarded and the gunn er is permitted to refire theexercise.

h. Decisions to disregard scores or to authorizerefiring of portions of the course rest w ith theofficer in charge.

i. If a misfire or malfunction is clearly the faultof the gunn er, he is not perm itted to refire thatportion of the course.

61. Scoring an Ind ividu al for Qu alification

a. A departu re from the man datory provisionsof this course d isqualifies the firer involved.

b. After a man h as started an exercise, all roun dsfired by him count as part of the exercise.

c. A gun ner is given credit for only those hitsthat strike the correct target or scoring space.

d. A hit is scored for each bullet hole found ina target or scoring space, except tha t no m ore thanthe prescribed nu mber of shots are coun ted. Infield service firing, observation of the strike on thetarget counts as a hit. The target does not haveto be marked.

e. For 25-meter firing, the name of the gunneris placed on each target before firing. Exceptunder the supervision of the scorer, no personhandles any target until it has been scored.

f. A bullet hole that touches the outer line of ascoring sp ace is classed as a h it. A bullet hole cut-ting or touching the line between two scoringspaces receives credit for the higher value score.

g. For moving target firing, ammunition notfired d uring the exposure tim e of this target isforfeited.

h. Holes made by ricocheting bu llets, rocks, orother foreign matter are not counted.

i. Each ind ividua l entry for record p ractice ismade on the scorecard in ink or indelible penciland is authenticated by the scorer. Erasures arenot perm itted; only the scorer can make alterationsand these must be initialed by him.

62. Safety Precaution sa. Because of the danger to p ersonnel from the

backblast of recoilless weapon, exercise extremecare in all phases of instruction. Emphasize thisdanger during the earliest stages of training. Con-duct all crew d rills, position exercises, trackingexercises, and subcaliber firing as though serviceamm un ition is being fired.

b. The backblast area is pentagonal in shape(fig. 32) with the apex at the breech. It extends140 feet to the rear and has a 180-foot base, 90 feeton either side of the bore axis extended. It isdivided into two areas: A danger area and a cau-tion area. In the danger area, which extends 90feet to the rear of the breech, serious casualties orfatalities are likely to occur du e to blast an d flyingdebris. In the caution area an individual is rela-tively safe provid ing he d oes not face the breech.This area extends an additional 50 feet to the rearof the danger area. It is hab itually kep t clear

during training situations.c. Do not fire the 90m m r ifle from confined

spaces such as d ugou ts or

downloaded from http://www.everyspec.com on 2010-01-25t16:18:56

Documents