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THEORY OF

MACHINE GUN

FIRE

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Terminal Learning Objective

• ACTION: Discuss the characteristics of Machine

Gun fire.

• CONDITIONS: GIVEN AN INSTRUCTOR,

CLASSROOM AND ACCESS TO FM 3-21.8 The

Infantry Rifle Platoon and Squad & FM 3-22.68

Crew-Served Machine Guns

• STANDARD: Discuss the characteristics of

Machine Gun fire IAW FM 3-21.8 The Infantry

Rifle Platoon and Squad & FM 3-22.68 Crew-

Served Machine Guns and achieve a minimum

passing score of 80% in overall testing.

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RISK ASSESSMENT

ENVIRONMENTAL

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REFERENCES

• FM 3-22.68

CREW SERVED MACHINE GUNS

5.56mm and 7.62mm (July 2006)

• FM 3-21.8 ANNEX A,

THE INFANTRY RIFLE PLATOON

AND SQUAD (March 2007)

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Enabling Learning

Objective 1

• Action: STATE MACHINE GUN CHARACTERISTICS.

• Conditions: GIVEN INSTRUCTOR, CLASSROOM AND ACCESS TO REFERENCES.

• Standards: STATE MACHINE GUN CHARACTERISTICS IAW FM 3-21.8 & FM 3-22.68

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FALLACY

• ““““THE MACHINE GUN WILL

NEVER REPLACE THE HORSE

AS AN INSTRUMENT OF WAR””””.

•SIR DOUGLAS HAIG,

COMMANDER-IN-CHIEF

BRITISH EXPEDITIONARY FORCES

DECEMBER, 1915.

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FACTS

• WW1

– KIA 9 million

– WIA 12.5 million

– Total approx 22 million casualties

– 25% = 5.5 million• BATTLE OF THE SOMME (01 JUL 1916)

– Commonwealth KIA 19, 000

– Commonwealth WIA 38, 000

– British III Corps lost 80%

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• AAR from action in Somalia in 1993

verified that the 7.62mm machinegun is

still the IN PLT’s most lethal weapon

system

• The bulk of an IN PLT’s organic

firepower is provided by the 7.62mm

machinegun, especially in the

Operational Environment of today!

PRESENT DAY

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You the Platoon Leader are

responsible for the proper

employment and training of

the platoon’s machinegun

Operators!

INSTRUCTIONAL LEAD-IN

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AGENDA

• MG CHARACTERISTICS

• TERMINOLOGY

• CLASSES OF MG FIRE

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GENERAL DATA:

M249

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GENERAL DATA – M249

• CALIBER: 5.56mm • MAXIMUM RANGE: 3600m

• MAXIMUM EFFECTIVE RANGE:– BIPOD / POINT TARGETS 600m– TRIPOD / POINT TARGETS 800m– BIPOD / AREA TARGETS 800m– TRIPOD / AREA TARGETS 1000m– GRAZING FIRE 600m– SUPPRESSION 1000m

• RATES OF FIRE:SUSTAINED: 50 rpm in 3-5 round bursts / 10 min barrel chgRAPID: 100 rpm in 8-10 round bursts / 2 min barrel chgCYCLIC: 650 - 850 rpm continuous burst / 1 min bar. chg

FM 3-22.68

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GENERAL DATA:

M240B

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GENERAL DATA - M240B

• MAXIMUM RANGE: 3725m

• MAXIMUM EFFECTIVE RANGE: 1100m

• MAXIMUM GRAZING FIRE: 600m

• AREA TARGETS (bipod / tripod) 800m / 1800m

• POINT TARGETS (bipod / tripod) 600m / 800m

• MAXIMUM TRACER BURNOUT: 900m

• RATES OF FIRE:

– SUSTAINED: 100 rpm in 6-9 round bursts/10 min

– RAPID: 200 rpm in 10-13 round bursts/2 min

– CYCLIC: 650-950 rpm continuous/ 1 min

FM 3-22.68

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GENERAL DATA: 50 Cal, M2

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GENERAL DATA - M2

• AMMUNITION: BALL/TRACER AP/INCEND (API)/APIT

• MAXIMUM RANGE: 6764m

• MAXIMUM EFFECTIVE RANGES:

AREA TARGETS: 1830m

POINT TARGET, SINGLE SHOT: 1500m

GRAZING: 700m

• RATES OF FIRE:

– SUSTAINED AND RAPID: 40 rpm 6-9 round bursts/barrel change when

damaged or end of day

– CYCLIC: 450-550 rpm continuous burst

FM 3-21.8

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Enabling Learning Objective 2

• Action: STATE THEORY OF MG FIRE

TERMINOLOGY.

• Conditions: GIVEN INSTRUCTOR,

CLASSROOM AND ACCESS TO

REFERENCES.

• Standards: STATE THE THEORY OF MG FIRE

TERMINOLOGY IAW FM 3-21.8 & FM 3-22.68

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THEORY OF MG FIRE:

-TERMINOLOGY-

• LINE OF SIGHT

• TRAJECTORY

• BURST OF FIRE

• MAXIMUM ORDINATE

• CONE OF FIRE

• BEATEN ZONE

• DANGER SPACE

• SURFACE DANGER ZONE

• DEAD SPACE

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LINE OF SIGHT

AN IMAGINARY LINE, FROM THE

FIRERS EYE,THROUGH THE

SIGHTS, TO THE POINT OF AIM

ON THE TARGET.

FM 3-21.8

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BURST OF FIRE

A BURST OF FIRE IS A NUMBER OF

SUCCESSIVE ROUNDS FIRED WITH

THE SAME ELEVATION AND POINT

OF AIM WHEN THE TRIGGER IS

HELD TO THE REAR. THE NUMBER

OF ROUNDS IN A BURST CAN VARY,

DEPENDING ON THE TYPE OF FIRE

EMPLOYED.

FM 3-21.8

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TRAJECTORY

TRAJECTORY IS THE CURVED PATH

A ROUND TAKES DURING ITS FLIGHT.

THE TRAJECTORY OF A ROUND IS

AFFECTED BY SEVERAL FACTORS.

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MAXIMUM ORDINATE

MAXIMUM ORDINATE IS THE HIGHEST POINT ABOVE THE LINE OF SIGHT THE TRAJECTORY REACHES BETWEEN THE MUZZLE OF THE WEAPON AND THE BASE OF THE TARGET

ABOUT 2/3 OF THE WAY ALONG THE TRAJECTORY

AS THE RANGE INCREASES, SO DOES THE HEIGHT OF THE MAXIMUM ORDINATE.

MAXIMUM ORDINATE

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CONE OF FIRE

THE GROUP OF TRAJECTORIES RESULTING FROM A

BURST OF FIRE IS TERMED THE CONE OF FIRE.

WHEN A BURST OF FIRE STRIKES A VERTICAL

TARGET, THE ROUNDS WILL FORM A PATTERN, OVAL

IN SHAPE, WITH THE DENSITY OF SHOTS

DECREASING TOWARDS THE EDGES.

CONE OF FIRE

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BEATEN ZONE

THE ELLIPTICAL PATTERN FORMED WHEN THE

ROUNDS WITHIN THE CONE OF FIRE STRIKE THE

GROUND OR TARGET.

- OVAL OR CIGAR SHAPED

- DENSITY DECREASES TOWARDS THE EDGE

- EFFECTIVE BEATEN ZONE = 85% OF ROUNDS

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EFFECTS OF RANGE ON BEATEN ZONE

AS RANGE INCREASES…………………………………..

M240B

RANGE: 500m 1 X 110 m

RANGE: 1000m 2 X 75 m

RANGE: 1500m 3 X 55 m

RANGE: 2000m 4 X 50 m

FM 3-21.8

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EFFECTS OF GROUND ON THE BEATEN ZONE

STEEP HILLSIDE

LEVEL GROUND

RISING SLOPE

CONFORMING GROUND

FM 3-21.8 pg A-10

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DANGER SPACE

THE SPACE BETWEEN THE MUZZLE

OF THE WEAPON AND THE TARGET

INCLUDING THE BEATEN ZONE.

WHERE THE TRAJECTORY RISES NO

MORE THAN 1.8m.

MAX 1.8m

DANGER SPACE

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SURFACE DANGER ZONE (SDZs)

• DEVELOPED FOR EACH WEAPON

• FRONT, BACK OR SIDE OF THE

MUZZLE

• INCLUDES IMPACT, DISPERSION

AND RICOCHET AREAS

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Ricochet

Area

Dis

tan

ce

Y

Dis

tan

ce

X

Dispersion

Area

Machine Gun SDZ

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DEAD SPACE

ANY FOLD OR DEPRESSION IN THE

GROUND THAT PREVENTS A

TARGET FROM BEING ENGAGED

FROM A FIXED POSITION IS

TERMED DEAD SPACE.

DEAD

SPACE

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Enabling Learning

Objective 3

• Action: STATE CLASSES OF MG FIRE.

• Conditions: GIVEN INSTRUCTOR,

CLASSROOM AND ACCESS TO

REFERENCES.

• Standards: STATE CLASSES OF MG

FIRE IAW FM 3-21.8 ANNEX A

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CLASSES OF MG FIRE

• WITH RESPECT TO THE GROUND– GRAZING FIRES

– PLUNGING FIRES

• WITH RESPECT TO THE TARGET– FRONTAL

– FLANKING

– OBLIQUE

– ENFILADE

• WITH RESPECT TO THE WEAPON– FIXED

– TRAVERSE

– SEARCH

– TRAVERSE AND SEARCH

– SWINGING TRAVERSE

– FREE GUN

FM 3-21.8

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CLASSES OF FIRE

WITH RESPECT TO

THE GROUND

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GRAZING FIRES

Level or conforming ground

- Center of cone 1m high

- Effective to 600m

- Danger space

CONE OF FIRE

DANGER SPACE

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PLUNGING FIRES

PLUNGING FIRE IS ACHIEVED WHEN THE DANGEROUS

ZONE IS PRACTICALLY CONFINED TO THE BEATEN ZONE. IT

IS OBTAINED WHEN FIRING AT VERY LONG RANGES, FROM

HIGH GROUND INTO LOW GROUND OR INTO ABRUPTLY

RISING GROUND.

CONE OF FIRE

DANGER

SPACE

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CLASSES OF FIRE

WITH RESPECT

TO THE TARGET

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CLASSES OF FIRE WITH

RESPECT TO TARGET

• FRONTAL FIRE:

–Occurs when the long axis of

the beaten zone is at a right

angle to the front of the

target.

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FRONTAL FIRE

LINE COLUMN

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CLASSES OF FIRE WITH

RESPECT TO TARGET

• FLANKING FIRE:

–Fire that is delivered directly

against the flank of the target.

FM 3-21.8

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FLANKING FIRE

LINECOLUMN

FM 3-21.8

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CLASSES OF FIRE WITH RESPECT

TO TARGET

• OBLIQUE FIRE:

–When the long axis of the

beaten zone is at an angle

other than a right angle to the

front of the target.

FM 3-21.8

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OBLIQUE FIRE

LINECOLUMN

FM 3-21.8

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CLASSES OF FIRE WITH RESPECT

TO TARGET

• ENFILADE FIRE: When the long

axis of the beaten zone coincides

or nearly coincides with the long

axis of the target. It is the

type of fire with respect

to a target because it makes

maximum use of the beaten zone.

FM 3-21.8

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ENFILADE FIRE

FRONTAL

ENFILADE

FLANKING

ENFILADE

FM 3-21.8

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CLASSES OF FIRE

WITH RESPECT TO

THE GUN

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CLASSES OF FIRE WITH RESPECT TO THE GUN

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FIXED FIRE

DELIVERED AGAINST A

STATIONARY POINT TARGET

WHEN THE DEPTH AND WIDTH

OF THE BEATEN ZONE WILL

COVER THE TARGET

FM 3-21.8

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TRAVERSE FIRE

TRAVERSING DISPERSES

FIRES IN WIDTH BY

SUCCESSIVE CHANGES IN

DIRECTION, BUT NOT

ELEVATION.

FM 3-21.8

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SEARCHING FIRE

SEARCHING DISTRIBUTES FIRES IN

DEPTH BY SUCCESSIVE CHANGES

IN ELEVATION.

FM 3-21.8

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TRAVERSING AND SEARCHING FIRE

IS A COMBINATION IN

WHICH SUCCESSIVE

CHANGES IN DIRECTION

AND ELEVATION RESULT IN

THE DISTRIBUTION OF

FIRES BOTH IN WIDTH AND

DEPTH

FM 3-21.8

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SWINGING TRAVERSE

IS EMPLOYED AGAINST

TARGETS THAT REQUIRE

MAJOR CHANGES IN

DIRECTION BUT LITTLE OR

NO CHANGE IN ELEVATION.

FM 3-21.8

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FREE GUN

IS DELIVERED AGAINST

MOVING TARGETS THAT

MUST BE RAPIDLY

ENGAGED WITH FAST

CHANGES IN BOTH

DIRECTION AND

ELEVATION.

FM 3-21.8

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