m240b machine gun operators course. overviewi orientation and mechanical training ii techniques of...

M240B Machine GunM240B Machine Gun

Operators CourseOperators Course

M240B Machine GunM240B Machine GunOperators CourseOperators Course

OVERVIEWOVERVIEW

II

Orientation and Mechanical TrainingOrientation and Mechanical Training

IIII

Techniques of Fire and EmploymentTechniques of Fire and Employment

IIIIII

Preparatory Marksmanship TrainingPreparatory Marksmanship Training


OVERVIEW CONTINUEDOVERVIEW CONTINUED

IVIV

Performance EvaluationPerformance Evaluation

VIVI

LIVE FIRE (Practice & Evaluation)LIVE FIRE (Practice & Evaluation)


OPRENTATION AND MECHANICAL TRAININGOPRENTATION AND MECHANICAL TRAINING

Basic Weapons Safety RulesBasic Weapons Safety Rules

1. Treat every Weapons as if it were 1. Treat every Weapons as if it were Loaded!Loaded!

2. Never point a weapon at anything you don’t 2. Never point a weapon at anything you don’t intend to shoot. intend to shoot.


3. Keep your finger off the trigger until your 3. Keep your finger off the trigger until your weapon is pointed down range and your weapon is pointed down range and your sight are on target.sight are on target.

4. Don’t shoot anything you can’t positively 4. Don’t shoot anything you can’t positively identify; know what is behind it.identify; know what is behind it.


5. Always carry your weapons so that you can 5. Always carry your weapons so that you can control the direction of the muzzle, even if you control the direction of the muzzle, even if you stumble.stumble.


CLASSROOM SAFETY RULESCLASSROOM SAFETY RULES

AND PROCEDURESAND PROCEDURES

1. Do not intentionally point the weapon at 1. Do not intentionally point the weapon at yourself or others during weapon yourself or others during weapon handling exerciseshandling exercises

(some pointing during training is (some pointing during training is unavoidable as weapons are cleared and unavoidable as weapons are cleared and made safe).made safe).


2. Handle the weapon only when told to do 2. Handle the weapon only when told to do so.so.

3. No horseplay of any kind allowed.3. No horseplay of any kind allowed.

4. Do not get ahead of the instructor or 4. Do not get ahead of the instructor or anticipate instructions.anticipate instructions.

5. Don’t let the bolt slam forward on an 5. Don’t let the bolt slam forward on an empty chamberempty chamber


6. If at any time, you don’t understand the 6. If at any time, you don’t understand the instruction or have difficulty or have instruction or have difficulty or have difficulty understanding an operation or a difficulty understanding an operation or a procedure, ask questions.procedure, ask questions.


M240B Machine Gun SafetyM240B Machine Gun Safety

1. Make sure the barrel is locked tightly 1. Make sure the barrel is locked tightly before firing.before firing.

2. Ensure the assigned/spare barrels have 2. Ensure the assigned/spare barrels have been headspaced and tagged to your been headspaced and tagged to your receiver. Rotate usage of the barrels.receiver. Rotate usage of the barrels.



3. Do not interchange barrel assembly or 3. Do not interchange barrel assembly or bolt assembly from one machine gun to bolt assembly from one machine gun to another. another. Doing so may result in injury to. Doing so may result in injury to. Or death of , personnel.Or death of , personnel.

4. Never reload a runaway machine gun 4. Never reload a runaway machine gun until it is repaired. Be sure machine gun is until it is repaired. Be sure machine gun is cleared before removing it from a vehicle cleared before removing it from a vehicle or tripod Mount.or tripod Mount.



5. A hot barrel can burn you. If barrel is hot, 5. A hot barrel can burn you. If barrel is hot, use your heat resistant mittens. use your heat resistant mittens.


M240B Machine Gun CharacteristicsM240B Machine Gun Characteristics

DescriptionDescription

1. Air cooled1. Air cooled

2. Belt-fed2. Belt-fed

3. Gas operated3. Gas operated

4. Fixed headspace.4. Fixed headspace.

Allows for quick barrel changes for cooling Allows for quick barrel changes for cooling and Maintenance and Maintenance


5. Fires from the open bolt position.5. Fires from the open bolt position.

6. 7.62mm NATO (.308 caliber).6. 7.62mm NATO (.308 caliber).

7. Weight – 27.6 lb. (12.52 kg)7. Weight – 27.6 lb. (12.52 kg)

8. Length – 49.0 inches (overall).8. Length – 49.0 inches (overall).


PerformancePerformance

RangeRange

Maximum adjustable – 1,800 metersMaximum adjustable – 1,800 meters

Maximum – 3,725 metersMaximum – 3,725 meters

Maximum effective rangeMaximum effective range

1. Point target – 800 meters with M122A1 1. Point target – 800 meters with M122A1 tripod.tripod.

2. Area target – 1,800 with M122A1 tripod. 2. Area target – 1,800 with M122A1 tripod. (Tracer burnout 900 meters) (Tracer burnout 900 meters)


Rates of FireRates of FireSustainedSustained – 100 RPM (6-9 rd. burst with4-5 – 100 RPM (6-9 rd. burst with4-5

sec. between bursts). Barrel change every sec. between bursts). Barrel change every 10 minutes.10 minutes.

RapidRapid – 200 RPM (6-9 rd. burst with 2-3 – 200 RPM (6-9 rd. burst with 2-3 seconds between bursts). Barrel change seconds between bursts). Barrel change every 2 minutesevery 2 minutes

CyclicCyclic – 650 to 950 RPM. Barrel change – 650 to 950 RPM. Barrel change every minute.every minute.


NOTENOTE

The M240B Machine gun was not intended The M240B Machine gun was not intended to fire at 950 RPM. This will cause to fire at 950 RPM. This will cause accelerated wear/damage to the barrel accelerated wear/damage to the barrel and the rest of the weapon. Gas inlet and the rest of the weapon. Gas inlet setting #1 is the preferred setting for setting #1 is the preferred setting for normal operating conditions. If gas normal operating conditions. If gas regulator plug has been set to #2 or 3 to regulator plug has been set to #2 or 3 to increase firing rate return it to the primary increase firing rate return it to the primary setting ASAP.setting ASAP.


AMMUNITION TYPES, CARE & HANDLINGAMMUNITION TYPES, CARE & HANDLING



(1) (1) Cartridge, 7.62-mm BallCartridge, 7.62-mm Ball M80-for use against light materials -for use against light materials and personnel, and for range training.and personnel, and for range training.(2) (2) Cartridge, 7.62-mm Armor-PiercingCartridge, 7.62-mm Armor-Piercing M61M61-for use against -for use against lightly armored targets.lightly armored targets.(3) (3) Cartridge, 7.62-mm Tracer Cartridge, 7.62-mm Tracer M62M62-for observation of fire, -for observation of fire, incendiary effects, signaling, and for training. When tracer incendiary effects, signaling, and for training. When tracer rounds are fired, they are mixed with ball ammunition in a ratio rounds are fired, they are mixed with ball ammunition in a ratio of four ball rounds to one tracer round.of four ball rounds to one tracer round.(4) (4) Cartridge, 7.62-mm DummyCartridge, 7.62-mm Dummy M63M63-for use during mechanical -for use during mechanical training.training.(5) (5) Cartridge, 7.62-mm BlankCartridge, 7.62-mm Blank M82 M82-for use during training -for use during training when simulated live fire is desired. A BFA should be used to when simulated live fire is desired. A BFA should be used to fire this ammunition.fire this ammunition.


AMMUNITION TYPES, CARE & HANDLINGAMMUNITION TYPES, CARE & HANDLING Storage. Ammunition is stored under cover. If ammunition is in the open, it must be kept at least 6 inches above the ground and covered with a double thickness of tarpaulin. The cover must be placed so that it protects the ammunition yet allows ventilation. Trenches are dug to divert water from flowing under the ammunition. Care, Handling, and Preservation. Ammunition should not be removed from the airtight containers until ready for use. Ammunition removed from the airtight containers, particularly in damp climates, may corrode.



Packaging The ammunition box contains two cartons. Each carton has a bandoleer for carrying purposes. Each carton contains 100 rounds and weighs about 7 pounds. Ammunition in the bandoleers may be linked together, attached to the hanger assembly, and fired from the container or the bandoleers may be removed for firing.


NOMENCLATURENOMENCLATURE

Major ComponentsMajor Components

1. Barrel Assembly1. Barrel Assembly

2. Buffer Assembly2. Buffer Assembly

3. Driving Spring Rod Assembly3. Driving Spring Rod Assembly

4. Bold and Operating Rod Assembly4. Bold and Operating Rod Assembly

5. Trigger Housing Assembly5. Trigger Housing Assembly

6. Cover Assembly6. Cover Assembly

7. Feed Tray7. Feed Tray

8. Receiver Assembly8. Receiver Assembly


NomenclatureNomenclature


External NomenclatureExternal Nomenclature

1. Barrel Assembly 1. Barrel Assembly 2. Heat Shield 2. Heat Shield 3. Buttstock Buffer Assy. 3. Buttstock Buffer Assy.

4. Receiver Assembly 4. Receiver Assembly 5. Handguard Assy.5. Handguard Assy.6. Cocking Handle Assy. 6. Cocking Handle Assy. 7. Trigger Housing Assy.7. Trigger Housing Assy.8. Sling Assembly8. Sling Assembly9. Bipod9. Bipod10.Drive spring rod Assy.10.Drive spring rod Assy.11. Bolt/Op rod Assy.11. Bolt/Op rod Assy.12. Cover Assembly12. Cover Assembly13. Feed Tray13. Feed Tray14.14.Tripod (not shown)Tripod (not shown)15.15. Ejection portEjection port

M240B Machine GunM240B Machine GunOperators CourseOperators CourseCycle of OperationCycle of Operation

Crew members can recognize and correct stoppages when Crew members can recognize and correct stoppages when they know how the weapon functions. The weapon they know how the weapon functions. The weapon

functions automatically as long as ammunition is fed into functions automatically as long as ammunition is fed into it and the trigger is held to the rear. Each time a round is it and the trigger is held to the rear. Each time a round is

fired, the parts of the weapon function in a cycle or fired, the parts of the weapon function in a cycle or sequence. Many of the actions occur at the same time sequence. Many of the actions occur at the same time

and are separated only for teaching purposes. The and are separated only for teaching purposes. The sequence of functioning is known as the "cycle of sequence of functioning is known as the "cycle of

functioning."functioning."


(1) (1) FeedingFeeding.. The actuating roller moves the feed lever The actuating roller moves the feed lever side to side, which in turn moves the feed pawls. The side to side, which in turn moves the feed pawls. The forward movement of the bolt forces the outer pawls to forward movement of the bolt forces the outer pawls to the right, fully feeding the round. The inner pawl rides the right, fully feeding the round. The inner pawl rides over the round and settles behind it. The rearward over the round and settles behind it. The rearward movement forces the inner pawl to the right, fully feeding movement forces the inner pawl to the right, fully feeding the round. The action of fully feeding a round pushes the the round. The action of fully feeding a round pushes the link of a fired round out of the side of the gun. The last link of a fired round out of the side of the gun. The last link in a belt cannot be pushed out and is cleared during link in a belt cannot be pushed out and is cleared during the unloading.the unloading.


(2) (2) ChamberingChambering.. The first round is positioned in line with The first round is positioned in line with the chamber and is held in position by the cartridge stop the chamber and is held in position by the cartridge stop and cartridge guide pawl. On trigger squeeze, the nose of and cartridge guide pawl. On trigger squeeze, the nose of the sear is depressed thus freeing the piston rod the sear is depressed thus freeing the piston rod extension. The driving spring rod assembly pushes the extension. The driving spring rod assembly pushes the working parts forward. The feed horn strikes the base of working parts forward. The feed horn strikes the base of the round. The bolt strips the round from the belt link. The the round. The bolt strips the round from the belt link. The chambering ramp angles downward and, along with the chambering ramp angles downward and, along with the spring tension of the cartridge guide pawl, forces the spring tension of the cartridge guide pawl, forces the round toward the chamber. The cartridge guide pawl also round toward the chamber. The cartridge guide pawl also holds back the belt link. When the round is fully seated in holds back the belt link. When the round is fully seated in the chamber, the extractor snaps over the extractor rim of the chamber, the extractor snaps over the extractor rim of the cartridge, and the ejector is depressed.the cartridge, and the ejector is depressed.


(3) (3) LockingLocking.. During chambering, as soon as the piston During chambering, as soon as the piston begins to move, the firing pin is withdrawn into the bolt begins to move, the firing pin is withdrawn into the bolt block. The breech remains locked during the primary block. The breech remains locked during the primary movement. The bolt enters the barrel breech as the movement. The bolt enters the barrel breech as the operating rod is driven forward by the drive spring, and operating rod is driven forward by the drive spring, and as the locking lever, which the bolt is riding on, swings as the locking lever, which the bolt is riding on, swings forward, pushing the bolt forward and locking it to the forward, pushing the bolt forward and locking it to the barrel breech. Although the term "locking" is used here, barrel breech. Although the term "locking" is used here, in the M240B, the bolt and barrel do not physically in the M240B, the bolt and barrel do not physically interlock. This way, the barrel can be removed when the interlock. This way, the barrel can be removed when the bolt is forward.bolt is forward.


(4) (4) FiringFiring.. As the working parts come forward and the As the working parts come forward and the round is fed into the chamber, the locking lever is forced round is fed into the chamber, the locking lever is forced down by the locking cams. This slows down the forward down by the locking cams. This slows down the forward movement of the bolt assembly. The piston rod movement of the bolt assembly. The piston rod extension, still moving forward, causes the locking lever extension, still moving forward, causes the locking lever link to rotate downward and back. This forces the arms link to rotate downward and back. This forces the arms down to their fullest extent in front of the locking down to their fullest extent in front of the locking shoulder. The extractor rises over the base of the round shoulder. The extractor rises over the base of the round and the ejector is compressed. The round is now fully and the ejector is compressed. The round is now fully home with the breech locked. The final forward home with the breech locked. The final forward movement of the piston extension drives the firing pin movement of the piston extension drives the firing pin through the bolt assembly onto the cartridge primer and through the bolt assembly onto the cartridge primer and fires the round. The working parts are now fully forward.fires the round. The working parts are now fully forward.


(5) (5) UnlockingUnlocking.. When the round is fired, some of the When the round is fired, some of the gases pass through the gas plug regulator into the gas gases pass through the gas plug regulator into the gas cylinder. The rapidly expanding gases enter the hollow cylinder. The rapidly expanding gases enter the hollow end cap of the gas piston and force the operating end cap of the gas piston and force the operating assembly to the rear. This powers the last four steps in assembly to the rear. This powers the last four steps in the cycle of functioning. During the primary movement of the cycle of functioning. During the primary movement of the operating rod assembly, it moves independently of the operating rod assembly, it moves independently of the bolt for a short distance. At this point, the locking the bolt for a short distance. At this point, the locking lever begins to swing toward the rear, carrying the bolt lever begins to swing toward the rear, carrying the bolt with it into its unlocked position, and clearing the barrel with it into its unlocked position, and clearing the barrel breech. When the bolt assembly has been jerked back, breech. When the bolt assembly has been jerked back, slightly enough to unlock the breech, the primary effort is slightly enough to unlock the breech, the primary effort is extraction of the empty case.extraction of the empty case.


(6) (6) ExtractionExtraction.. When the breech is fully unlocked and When the breech is fully unlocked and the bolt assembly starts its rearward movement, the the bolt assembly starts its rearward movement, the extractor withdraws the empty case from the extractor withdraws the empty case from the chamber.chamber.


(7) (7) Ejecting.Ejecting. As the cartridge case is withdrawn from the As the cartridge case is withdrawn from the chamber, the ejector pushes from the top, and the chamber, the ejector pushes from the top, and the extractor pulls from the bottom. The casing falls down extractor pulls from the bottom. The casing falls down from the face of the bolt as soon as it reaches the from the face of the bolt as soon as it reaches the cartridge-ejection port. The empty belt links are forced cartridge-ejection port. The empty belt links are forced out the link ejection port as the rearward movement of out the link ejection port as the rearward movement of the bolt causes the next round to be positioned in the the bolt causes the next round to be positioned in the tray groove.tray groove.


(8) (8) CockingCocking.. As the working parts continue toward the As the working parts continue toward the rear, the return spring is compressed; the trigger is kept rear, the return spring is compressed; the trigger is kept squeezed; sufficient is gas made available by the gas-squeezed; sufficient is gas made available by the gas-regulator adjustment, which causes the working parts to regulator adjustment, which causes the working parts to rebound off the buffer; and the action of feeding and rebound off the buffer; and the action of feeding and firing continues. In releasing the trigger, the sear remains firing continues. In releasing the trigger, the sear remains down, but the tripping lever rises. As the working parts down, but the tripping lever rises. As the working parts come to the rear, the end of the piston rod extensioncome to the rear, the end of the piston rod extension


Clearing ProceduresClearing Procedures

1. Move Safety to 1. Move Safety to Fire positionFire position

2.Pull cocking 2.Pull cocking handle assembly handle assembly to rear, locking to rear, locking bolt to rear, and bolt to rear, and return cocking return cocking handle forward.handle forward.


Clearing Procedures cont.Clearing Procedures cont.

3. Safety lever to safe3. Safety lever to safe4. Push in latches & open 4. Push in latches & open

cover assemblycover assembly5. Remove Ammo (if 5. Remove Ammo (if

present)present)6. Check the Five Points of 6. Check the Five Points of

SafetySafety (1) Feed Pawl (1) Feed Pawl

AssemblyAssembly (2) Feed Tray(2) Feed Tray (3) Chamber(3) Chamber (4) Space between the Bolt (4) Space between the Bolt

face and Chamberface and Chamber (5) Space under the Bolt (5) Space under the Bolt

and Operating Rod and Operating Rod AssemblyAssembly

7. Safety to Fire7. Safety to Fire


Clearing Procedures cont.Clearing Procedures cont.

8. Hold cocking handle to rear , depress 8. Hold cocking handle to rear , depress trigger, and ride bolt forward to close and trigger, and ride bolt forward to close and lock. lock.

9. Close cover assembly Ensure it locks shut9. Close cover assembly Ensure it locks shut

NOTE:NOTE:Be sure bolt is forward with safety to “F” Be sure bolt is forward with safety to “F” (fire position) when gun is not in use.(fire position) when gun is not in use.


LOADINGLOADING

1.1. Safety to Fire.Safety to Fire.2.2. Lock bolt to rear and return Lock bolt to rear and return

cocking handle forward.cocking handle forward.3.3. Safety to Safe.Safety to Safe.4.4. Raise Cover & clear Raise Cover & clear

ChamberChamber5.5. Place on Fire and move bolt Place on Fire and move bolt

forwardforward6.6. Place link belt in feed tray Place link belt in feed tray

with first round against with first round against cartridge stopcartridge stop

7.7. Close cover, make sure it Close cover, make sure it locks shut.locks shut.

8.8. Pull cocking handle to rear Pull cocking handle to rear and return handle forward.and return handle forward.

9.9. If weapon is not to be fired If weapon is not to be fired immediately place safety on immediately place safety on Safe. Safe.


UnloadingUnloading

Unload the M240B by pulling and locking the Unload the M240B by pulling and locking the bolt to the rear position, if it is not already bolt to the rear position, if it is not already there. Manually return the cocking handle to there. Manually return the cocking handle to its forward position. Places the safety on "S." its forward position. Places the safety on "S." Raise the cover assembly and remove any Raise the cover assembly and remove any ammunition or links from the feed tray.ammunition or links from the feed tray.

(This is also considered the “Rack Safe” Condition)(This is also considered the “Rack Safe” Condition)

M240B Machine GunM240B Machine GunField Strip (Disassembly)Field Strip (Disassembly)

Clear WeaponClear Weapon(a) Depress barrel (a) Depress barrel

locking latch and locking latch and hold.hold.

(b) Turn barrel (b) Turn barrel release/carrying release/carrying handle to upright handle to upright position. position. (Caution; (Caution; Be sure bolt is Be sure bolt is forward) forward)

(c) Remove Barrel. (c) Remove Barrel. Push Forward and Push Forward and lift barrel out.lift barrel out.


5. Remove Heat Shield 5. Remove Heat Shield assembly from assembly from barrel. (c) Lift rear of barrel. (c) Lift rear of heat shield off barrel heat shield off barrel then pry (d) front then pry (d) front tabs out of holes on tabs out of holes on gas hole bushing.gas hole bushing.


Remove the Remove the Buttstock and Buttstock and Buffer Assembly.Buffer Assembly. Depress the back Depress the back plate latch located plate latch located on the underside of on the underside of the butt stock the butt stock where it joins the where it joins the receiver. Slide the receiver. Slide the butt stock upward butt stock upward (straight up) and (straight up) and remove it from the remove it from the receiverreceiver


Remove the Driving Remove the Driving Spring Rod Spring Rod Assembly.Assembly.

Push the driving Push the driving spring rod spring rod assembly forward assembly forward and up to and up to disengage its disengage its retaining stud retaining stud from inside the from inside the receiver. Pull receiver. Pull rearward on the rearward on the drive spring rod drive spring rod assembly, assembly, removing it from removing it from the receiverthe receiver


Remove the Bolt and Operating Remove the Bolt and Operating Rod Assembly.Rod Assembly.

Pull the cocking handle to the Pull the cocking handle to the rear to start the rearward rear to start the rearward movement of the bolt and movement of the bolt and operating rod assembly operating rod assembly

inside of the receiver. With inside of the receiver. With the index finger, reach the index finger, reach

inside the top of the receiver inside the top of the receiver and push rearward on the and push rearward on the

face of the bolt until the bolt face of the bolt until the bolt and operating rod assembly and operating rod assembly

are exposed at the rear of are exposed at the rear of the receiver. Grasp the bolt the receiver. Grasp the bolt

and operating rod and and operating rod and remove them from the rear remove them from the rear of the receiver. Return the of the receiver. Return the

cocking handle to the cocking handle to the forward positionforward position


Remove the Trigger Remove the Trigger Housing Assembly.Housing Assembly.

Depress spring pin and Depress spring pin and remove. You may remove. You may

need to use the back need to use the back of the back plate of of the back plate of the buttstock to tap the buttstock to tap on the spring pin, on the spring pin,

then remove pin with then remove pin with fingers. All pins go fingers. All pins go from right to left. from right to left.


Rotate the rear of Rotate the rear of the trigger-the trigger-

housing group housing group assembly down, assembly down, disengage the disengage the

holding notch at holding notch at the front of the the front of the assembly from assembly from

its recess on the its recess on the bottom of the bottom of the receiver, and receiver, and remove the remove the

assembly from assembly from the receiverthe receiver


Remove the Cover Remove the Cover Assembly.Assembly.

(A) Close cover. Depress (A) Close cover. Depress spring pin and remove. spring pin and remove.

You may need to use the You may need to use the back of the back plate of back of the back plate of the buttstock to tap on the buttstock to tap on the spring pin. (B) Then the spring pin. (B) Then remove pin with fingers. remove pin with fingers. All pins go from right to All pins go from right to left. (C) Depress cover left. (C) Depress cover

latches, lift upwards and latches, lift upwards and remove cover assembly. remove cover assembly.

(D) Remove feed tray(D) Remove feed tray

M240B Machine GunM240B Machine GunAssemblyAssembly

Replacing the Cover Assembly and Feed Tray.Replacing the Cover Assembly and Feed Tray.

Position the feed tray on the receiver so that the Position the feed tray on the receiver so that the feed tray guides are aligned with the receiver feed tray guides are aligned with the receiver brackets. Place the cover assembly onto the brackets. Place the cover assembly onto the receiver aligning its mounting holes with the receiver aligning its mounting holes with the

mounting brackets on the receiver, close the cover mounting brackets on the receiver, close the cover assembly. Then, insert the spring pin into the assembly. Then, insert the spring pin into the

holes to affix the cover and feed tray to the holes to affix the cover and feed tray to the receiver (insert the spring of the spring pin into receiver (insert the spring of the spring pin into

the hole than push in from right to left).the hole than push in from right to left).


Replacing the Trigger Housing AssemblyReplacing the Trigger Housing Assembly..

Insert the holding notch on the front of the trigger Insert the holding notch on the front of the trigger housing into the forward recess on the bottom of housing into the forward recess on the bottom of the receiver. Rotate the rear of the trigger the receiver. Rotate the rear of the trigger housing upwards and align the holes of the housing upwards and align the holes of the trigger housing with the mounting bracket on the trigger housing with the mounting bracket on the receiver. Hold the trigger housing assembly and receiver. Hold the trigger housing assembly and insert the spring pin into the hole, securing the insert the spring pin into the hole, securing the assembly to the receiver. (insert the spring of assembly to the receiver. (insert the spring of the spring pin into the hole than push in from the spring pin into the hole than push in from right to left)right to left)


Replacing Replacing TriggerTriggerHousing Housing AssemblyAssembly


Replacing the Bolt and Operating Rod Replacing the Bolt and Operating Rod AssemblyAssembly..

Make sure the bolt and operating rod are fully Make sure the bolt and operating rod are fully extended (unlocked position). Insert the bolt and extended (unlocked position). Insert the bolt and operating rod into the rear of the receiver (bolt operating rod into the rear of the receiver (bolt

upward, operating rod beneath bolt) ensuring the upward, operating rod beneath bolt) ensuring the bolt is on top of the rails located on the left and bolt is on top of the rails located on the left and right inner walls of the receiver. Push the entire right inner walls of the receiver. Push the entire

bolt and operating rod assembly into the bolt and operating rod assembly into the receiver as far forward as possible. Pull the receiver as far forward as possible. Pull the

trigger to allow the sear to drop and the group to trigger to allow the sear to drop and the group to slide all the way into the receiverslide all the way into the receiver


Replacing Bolt and Operating Replacing Bolt and Operating Rod AssemblyRod Assembly


Replacing the Driving Replacing the Driving Spring Rod AssemblySpring Rod Assembly..

Insert the driving spring Insert the driving spring rod assembly into the rod assembly into the

receiver, sliding it all the receiver, sliding it all the way forward against the way forward against the recess in the rear of the recess in the rear of the operating rod. Push in operating rod. Push in and lower the driving and lower the driving

spring rod assembly to spring rod assembly to engage the retaining engage the retaining

stud into the hole stud into the hole located on the bottom of located on the bottom of

the receiverthe receiver


Replacing the Butt Replacing the Butt stock and Buffer stock and Buffer

Assembly.Assembly. Position the bottom Position the bottom

recess grooves of recess grooves of the butt stock onto the butt stock onto

the top of the the top of the receiver recess receiver recess

grooves. Slide the grooves. Slide the butt stock down butt stock down

until it locks in place until it locks in place on the receiver. on the receiver. Ensure the butt Ensure the butt stock is secure.stock is secure.


Replacing the Barrel AssemblyReplacing the Barrel Assembly. . Insert the gas regulator plug into the gas Insert the gas regulator plug into the gas

hole bushing so that it is on the number one hole bushing so that it is on the number one setting.setting.

Place the gas collar over the front end of the Place the gas collar over the front end of the gas regulator plug, while pushing against the gas regulator plug, while pushing against the spring, rotate counterclockwise until it stopsspring, rotate counterclockwise until it stops

Insert one of the metal tabs of the heat shield Insert one of the metal tabs of the heat shield in to the hole located on the sides of the gas in to the hole located on the sides of the gas hole bushing, than rotate it until the other tab hole bushing, than rotate it until the other tab locks in placelocks in place


Push down on the heat shield so that it Push down on the heat shield so that it snaps onto the barrel.snaps onto the barrel.

With the gas regulator downward and With the gas regulator downward and carrying handle in the vertical position, place carrying handle in the vertical position, place barrel on the barrel support (located on the barrel on the barrel support (located on the gas cylinder).gas cylinder).

Keeping the gun upright, pull the barrel to Keeping the gun upright, pull the barrel to the rear ensuring the gas regulator is guided the rear ensuring the gas regulator is guided into the gas cylinder. into the gas cylinder.


Pull the barrel fully into the receiver and Pull the barrel fully into the receiver and rotate the carrying handle completely to the rotate the carrying handle completely to the right, ensuring to count the number of clicks.right, ensuring to count the number of clicks.

If the number of clicks fall between 2 & 7, the If the number of clicks fall between 2 & 7, the headspace is set correctly.headspace is set correctly.

If the number falls outside 2 to 7, turn it in to If the number falls outside 2 to 7, turn it in to Combat Arms personnel. Combat Arms personnel.

M240B Machine GunM240B Machine GunFunction CheckFunction Check

Place the safety on "F."Place the safety on "F." Pull the cocking handle to the rear, locking Pull the cocking handle to the rear, locking

the bolt to the rear of the receiver. the bolt to the rear of the receiver. Return the cocking handle to the forward Return the cocking handle to the forward

position.position. Place the safety on "S," and closes the Place the safety on "S," and closes the

cover.cover. Pull the trigger. (Bolt should not go forward).Pull the trigger. (Bolt should not go forward). Place the safety on "F."Place the safety on "F." Pull the cocking handle to the rear, pulls the Pull the cocking handle to the rear, pulls the

trigger, and rides the bolt forward.trigger, and rides the bolt forward. Close the ejection port cover.Close the ejection port cover.

M240B Machine GunM240B Machine GunMalfunctions, Stoppages, Malfunctions, Stoppages,

MisfiresMisfiresand Immediate actions and Immediate actions

DefinitionsDefinitions Malfunction:Malfunction: A malfunction occurs when a A malfunction occurs when a

mechanical failuremechanical failure causes the weapon to fire causes the weapon to fire improperly. improperly.

Stoppage:Stoppage: Any interruption in the cycle of Any interruption in the cycle of operation of the gun.operation of the gun.

Immediate Action:Immediate Action: Prompt actions taken to Prompt actions taken to overcome the stoppage.overcome the stoppage.



DefinitionsDefinitions Remedial Action: Remedial Action: Action taken to identify Action taken to identify

stoppage, in immediate action fails.stoppage, in immediate action fails. Cook-off:Cook-off: Ignition of a chambered round of Ignition of a chambered round of

ammunition due to the heat of the weapon.ammunition due to the heat of the weapon.Hot or Cold gun: Hot or Cold gun: (Peacetime classification only (Peacetime classification only

in the interest of safety) in the interest of safety) Hot gun-Hot gun- more than 200 rounds fired within a 2 more than 200 rounds fired within a 2

minute periodminute period



WarningWarning

If nothing is ejected and you have a hot gun If nothing is ejected and you have a hot gun (200 rounds within a 2 minute period). Do not (200 rounds within a 2 minute period). Do not open the cover. Place safety to safe, keep open the cover. Place safety to safe, keep machine gun pointed down range, and machine gun pointed down range, and remain away from the weapon for 15 minutes. remain away from the weapon for 15 minutes. After 15 minutes clear the machine gun. The After 15 minutes clear the machine gun. The climate conditions can also affect how fast climate conditions can also affect how fast the weapons becomes “hot” the weapons becomes “hot”

M240B Machine GunM240B Machine GunMalfunctionsMalfunctions

Uncontrolled Fire (Runaway Gun)Uncontrolled Fire (Runaway Gun) Uncontrolled fire (the weapon continues to fire after Uncontrolled fire (the weapon continues to fire after

the trigger is released). This is usually caused by, the trigger is released). This is usually caused by, the gunner not pulling and holding the trigger all the gunner not pulling and holding the trigger all the way to the rear. The following are immediate the way to the rear. The following are immediate actions for uncontrolled fire:actions for uncontrolled fire:

(1) The gunner holds the weapon on target and (1) The gunner holds the weapon on target and fires the remaining ammunition.fires the remaining ammunition.

(2) The assistant gunner stops the weapon from (2) The assistant gunner stops the weapon from firing by breaking the belt of ammunition.firing by breaking the belt of ammunition.

(3) The gunner as a last resort pulls the cocking (3) The gunner as a last resort pulls the cocking handle to the rear thus, locking the bolt to the rear handle to the rear thus, locking the bolt to the rear of the receiver.of the receiver.

M240B Machine GunM240B Machine GunMalfunctionsMalfunctions

Sluggish OperationSluggish Operation

Sluggish operation is due to excessive Sluggish operation is due to excessive friction caused by carbon build-up, friction caused by carbon build-up, improper lubrication, or burred parts. improper lubrication, or burred parts. Corrective action includes cleaning, Corrective action includes cleaning, lubricating inspecting, and replacing lubricating inspecting, and replacing worn parts. The gunner may adjust the worn parts. The gunner may adjust the gas regulator to maintain the rate of fire gas regulator to maintain the rate of fire until he has a chance to clean the until he has a chance to clean the machine gun.machine gun.

M240B Machine GunM240B Machine GunStoppagesStoppages

STOPPAGESTOPPAGE PROBABLE CAUSE CORRECTIVE ACTION PROBABLE CAUSE CORRECTIVE ACTION

Failure to feed. Insufficient gas pressure.Improper lubrication.Defective links or ammunition.Ammunition belt installed wrong.Damaged or weak feed pawls and springs or feed lever.Obstruction in receiver.Damaged or weak feed pawls Defective links or ammunition.Ammunition belt installed wrong.

Clean gas port, inserts, and gas plug.Lubricate as required.Insert new link or ammunition.Reverse belt with open side of link down.Replace.Remove obstruction; clean and lubricate as required.Send to DS maintenance.Insert new link or ammunition.Reverse belt with open side of link down.



Failure to chamber. Ruptured cartridge case.Damaged driving spring rod assembly.

Damaged gas plug/collar (cracks/burrs).Built-up carbon on gas plug/collar, gas cylinder, piston or dirty chamber.

Remove and Replace driving spring rod assembly.

Replace gas plug/collar.Remove carbon and clean.



Failure to extract. Broken extractor or spring. Chipped or broken extractor. Defective extractor plunger. Insufficient gas pressure.

Replace.Replace.Replace.Clean and lubricate as required.

Failure to lock. Dirty Chamber.Dirty receiver or lack of lubrication.Insufficient gas pressure.

Clean WeaponClean and lubricate Clean gas regulator.

Failure to fire. Faulty ammunition.Broken or damaged firing pin or defective trigger.Insufficient gas pressure.

Replace.Replace or send to DS maintenance.Clean gas port, inserts, and gas plug.

M240B Machine GunM240B Machine Gun StoppagesStoppages


Failure to cock. Broken sear.Worn operating rod sear notch.Broken, defective, or missing sear plunger and or spring.

Send to DS maintenance.Send to DS maintenance.Send to DS maintenance.

Short to recoil. Clean gas port and operating rod tube. Lubricate as required. Replace operating rod spring. See runaway gun (Malfunctions).

M240B Machine GunM240B Machine GunImmediate ActionImmediate Action

Immediate actionImmediate action is action taken to is action taken to reduce a stoppage reduce a stoppage without looking without looking for the causefor the cause.. Immediate action Immediate action should be taken in the event of either should be taken in the event of either a a misfiremisfire or a or a cook offcook off. A . A misfiremisfire is is the failure of a chambered round to the failure of a chambered round to fire. Such failure can be due to an fire. Such failure can be due to an ammunition defect or faulty firing ammunition defect or faulty firing mechanism.mechanism.

M240B Machine GunM240B Machine GunImmediate ActionImmediate Action

A A cook offcook off is the firing of a round by the is the firing of a round by the heat of a hot barrel and not by the firing heat of a hot barrel and not by the firing mechanism. mechanism. CookoffsCookoffs can be avoided by can be avoided by applying immediate action within 10 applying immediate action within 10 seconds after a failure to fire. If the M240B seconds after a failure to fire. If the M240B stops firing, the gunner performs the stops firing, the gunner performs the following immediate actions are taken. (An following immediate actions are taken. (An effective memory aid is effective memory aid is POPPPOPP, which , which stands for stands for pullpull, , observeobserve,, push push, and , and presspress.).)

M240B Machine GunM240B Machine Gun Immediate ActionImmediate Action

a. Pulls and locks the cocking handle to the rear while a. Pulls and locks the cocking handle to the rear while observing the ejection port to see if a cartridge case, observing the ejection port to see if a cartridge case, belt link, or round is ejected. Ensures that the bolt belt link, or round is ejected. Ensures that the bolt remains to the rear to prevent double feeding if a remains to the rear to prevent double feeding if a round or cartridge case is not ejected.round or cartridge case is not ejected.

b. If a cartridge case, belt link, or a round is ejected, b. If a cartridge case, belt link, or a round is ejected, returns cocking handle to forward position, aim on returns cocking handle to forward position, aim on the target, and presses the trigger. If the weapon still the target, and presses the trigger. If the weapon still does not fire, takes remedial action. If a cartridge does not fire, takes remedial action. If a cartridge case, belt link, or round is not ejected, takes case, belt link, or round is not ejected, takes remedial action.remedial action.

M240B Machine GunM240B Machine GunRemedial ActionRemedial Action

Cold Weapon ProceduresCold Weapon Procedures When a stoppage occurs with a cold weapon and When a stoppage occurs with a cold weapon and

immediate action has failed, the gunner uses the immediate action has failed, the gunner uses the following procedures.following procedures.

(1) Pulls the cocking handle to the rear, locking the (1) Pulls the cocking handle to the rear, locking the bolt. Returns the cocking handle and places the bolt. Returns the cocking handle and places the safety to SAFE.safety to SAFE.

(2) Places the weapon on the ground or away from (2) Places the weapon on the ground or away from his face and opens the cover, performs the four-his face and opens the cover, performs the four-point safety check. Reloads and continues to fire.point safety check. Reloads and continues to fire.

(3) If the weapon does not fire, clears the weapon (3) If the weapon does not fire, clears the weapon and inspects it and the ammunition.and inspects it and the ammunition.

M240B Machine GunM240B Machine Gun Remedial ActionRemedial Action

Hot Weapon ProceduresHot Weapon Procedures

If the stoppage occurs with a hot weapon (200 If the stoppage occurs with a hot weapon (200 rounds or more in 2 minutes or as noted above for rounds or more in 2 minutes or as noted above for training), the gunner moves the safety to SAFE, training), the gunner moves the safety to SAFE, waits 5 seconds (during training, lets the weapon waits 5 seconds (during training, lets the weapon cool for 15 minutes), uses the same procedures as cool for 15 minutes), uses the same procedures as outlined for cold weapon procedures.outlined for cold weapon procedures.


Jammed Cocking HandleJammed Cocking Handle

If a stoppage occurs and the cocking handle If a stoppage occurs and the cocking handle cannot be pulled to the rear by hand (the bolt cannot be pulled to the rear by hand (the bolt may be fully forward and locked or only partially may be fully forward and locked or only partially forward), the gunner takes the following steps.forward), the gunner takes the following steps.

(1) Tries once again to pull the cocking handle (1) Tries once again to pull the cocking handle by by handhand. .

WARNINGWARNING

Do not try to force the cocking handle to the rear with your Do not try to force the cocking handle to the rear with your foot or a heavy object. This could damage the weapon.foot or a heavy object. This could damage the weapon.


(2) If the weapon is hot enough to cause a cook off, (2) If the weapon is hot enough to cause a cook off, moves all soldiers a safe distance from the moves all soldiers a safe distance from the weapon and keeps them away for 15 minutes.weapon and keeps them away for 15 minutes.

(3) After the gun has cooled, the gunner will pull (3) After the gun has cooled, the gunner will pull the cocking handle to the rear. Ensures rearward the cocking handle to the rear. Ensures rearward pressure is kept on the cocking handle until the pressure is kept on the cocking handle until the driving spring rod assembly is removed. Opens driving spring rod assembly is removed. Opens the cover and disassembles the gun. (The the cover and disassembles the gun. (The assistant gunner helps the gunner do this.)assistant gunner helps the gunner do this.)


(4) Removes the round or fired cartridge. Uses (4) Removes the round or fired cartridge. Uses cleaning rod or ruptured cartridge extractor if cleaning rod or ruptured cartridge extractor if necessary.necessary.

(a) In a training situation, after completing the (a) In a training situation, after completing the remedial action procedures, the gun should not be remedial action procedures, the gun should not be fired until an inspection by an ordnance specialist fired until an inspection by an ordnance specialist has been made.has been made.

(b) In a combat situation, after the stoppage has (b) In a combat situation, after the stoppage has been corrected, the gunner changes the barrel and been corrected, the gunner changes the barrel and tries to fire. If the weapon fails to function tries to fire. If the weapon fails to function properly, the gunner sends it to Combat Arms properly, the gunner sends it to Combat Arms personnel.personnel.

M240B Machine GunM240B Machine Gun Cleaning and Cleaning and

LubricationLubrication

WarningWarningBe sure weapons is cleared before disassembly, Be sure weapons is cleared before disassembly,

cleaning, inspecting, transporting and storing.cleaning, inspecting, transporting and storing.

Using gasoline, kerosene, hydraulic oil, benzene, Using gasoline, kerosene, hydraulic oil, benzene, bensol, high-pressure water, steam, or air forbensol, high-pressure water, steam, or air for

cleaning iscleaning is PROHIBITEDPROHIBITED



CautionCaution

Do not use abrasives to clean the bore, Do not use abrasives to clean the bore, piston, gas cylinder, or gas regulator plug.piston, gas cylinder, or gas regulator plug.

Do not submerge buffer in any liquid. Wipe Do not submerge buffer in any liquid. Wipe clean with wiping rag only.clean with wiping rag only.

Do not apply lubricants to composite/rubber Do not apply lubricants to composite/rubber components.components.



The M240B machine gun should be cleaned immediately after firing. At a minimum, the M240B should be cleaned after firing a basic load of 900 to 1,200 rounds. The gunner disassembles the M240B into its major groups for cleaning. All metal components and surfaces that have been exposed to powder fouling should be cleaned using CLP on a bore-cleaning patch. CLP is used on the bristles of the receiver brush to clean the receiver. After the M240B is cleaned and wiped dry, a thin coat of CLP is rubbed on using a cloth. This lubricates and preserves the exposed metal parts during all normal temperature ranges.



CAUTIONCAUTION

When using CLP, do not use other cleaners. When using CLP, do not use other cleaners. Never mix CLP with RBC or LSA. When Never mix CLP with RBC or LSA. When cleaning the barrel, avoid getting CLP or cleaning the barrel, avoid getting CLP or RBC in the gas regulator. Damage could RBC in the gas regulator. Damage could occur to the weapon.occur to the weapon.



(1) Clean the bore using CLP or RBC and a bore (1) Clean the bore using CLP or RBC and a bore brush with a cleaning rod. Do not reverse direction brush with a cleaning rod. Do not reverse direction of the bore brush while it is in the bore.of the bore brush while it is in the bore.

(a) Run the brush through the bore several times (a) Run the brush through the bore several times until most of the powder fouling and other foreign until most of the powder fouling and other foreign matter has been removed.matter has been removed.

(b) Swab out the bore several times using a (b) Swab out the bore several times using a cleaning rod and a swab wet with CLP.cleaning rod and a swab wet with CLP.

(c) Swab out the bore several times using a (c) Swab out the bore several times using a cleaning rod and a dry swab.cleaning rod and a dry swab.



(2) Clean the chamber using CLP and a chamber (2) Clean the chamber using CLP and a chamber brush attached to a cleaning rod.brush attached to a cleaning rod.

(a) Run the brush through the chamber several (a) Run the brush through the chamber several times until most of the powder fouling and other times until most of the powder fouling and other foreign matter has been removed.foreign matter has been removed.

(b) Swab out the chamber several times using a (b) Swab out the chamber several times using a cleaning rod and a swab wet with CLP.cleaning rod and a swab wet with CLP.

(c) Swab out the chamber several times using a (c) Swab out the chamber several times using a cleaning rod and a dry swab.cleaning rod and a dry swab.



(3) Clean the receiver using a receiver brush and (3) Clean the receiver using a receiver brush and CLP.CLP.

(a) Brush the receiver until most of the powder (a) Brush the receiver until most of the powder fouling and other foreign matter is removed.fouling and other foreign matter is removed.

(b) Swab out the receiver several times using a (b) Swab out the receiver several times using a cleaning rod section and a swab wet with CLP.cleaning rod section and a swab wet with CLP.

(c) Swab out the receiver several times using a cleaning rod section and a dry swab.



(4) Clean the gas regulator plug with special tools (cleaning (4) Clean the gas regulator plug with special tools (cleaning reamers and combination regulator scraper). Remove reamers and combination regulator scraper). Remove all all carbon dust. Do not use CLP on the collar, gas block, or carbon dust. Do not use CLP on the collar, gas block, or body.body.

(a) Clean each gas inlet hole of the gas regulator plug. Insert (a) Clean each gas inlet hole of the gas regulator plug. Insert the small reamer into each hole and twist back and forth to the small reamer into each hole and twist back and forth to remove the carbon (apply hand pressure only).remove the carbon (apply hand pressure only).

(b) Clean the central hole of the gas plug by inserting the (b) Clean the central hole of the gas plug by inserting the scraper tool down to the bottom of the hole and twisting scraper tool down to the bottom of the hole and twisting firmly.firmly.

(c) Clean the two grooves by inserting the scraper tool into (c) Clean the two grooves by inserting the scraper tool into the grooves and applying pressure as firmly as possible.the grooves and applying pressure as firmly as possible.



(5) Clean the gas cylinder with the special tool (5) Clean the gas cylinder with the special tool scraper-extraction combination tool.scraper-extraction combination tool.

(a) Clean the front interior of the gas cylinder by (a) Clean the front interior of the gas cylinder by carefully inserting the combination tool, with the carefully inserting the combination tool, with the handle upward. Be sure the tool is fully inserted handle upward. Be sure the tool is fully inserted and seated against the gas cylinder. Apply slight and seated against the gas cylinder. Apply slight pressure to the handles and turn clockwise to pressure to the handles and turn clockwise to remove carbon.remove carbon.

(b) Clean gas cylinder bore with gas cylinder (b) Clean gas cylinder bore with gas cylinder cleaning brush dampened with CLP.cleaning brush dampened with CLP.

(c) Brush the gas cylinder until most of the powder (c) Brush the gas cylinder until most of the powder fouling and other foreign matter are removed.fouling and other foreign matter are removed.



CAUTIONCAUTION When inserting the scraper-extractor combination tool into the gas cylinder, When inserting the scraper-extractor combination tool into the gas cylinder,

ensure before scraping that it is fully seated against the fore-end face of the ensure before scraping that it is fully seated against the fore-end face of the cylinder. Damage to the fore-end of the gas cylinder could cause gas leakage cylinder. Damage to the fore-end of the gas cylinder could cause gas leakage

and subsequent weapon stoppage.and subsequent weapon stoppage.



(6) Clean the bolt and operating rod with the special (6) Clean the bolt and operating rod with the special scraper-extraction combination tool.scraper-extraction combination tool.

(a) Clean the piston head cavity by inserting the (a) Clean the piston head cavity by inserting the combination tool into the piston bottom of the combination tool into the piston bottom of the operating rod. Squeeze handles firmly and twist the operating rod. Squeeze handles firmly and twist the tool to remove carbon.tool to remove carbon.

(b) Insert the screwdriver end of the tool into the (b) Insert the screwdriver end of the tool into the piston to remove carbon residue on the bottom.piston to remove carbon residue on the bottom.

(c) Clean the bolt and operating rod with rag and (c) Clean the bolt and operating rod with rag and CLP.CLP.



Cleaning tool of the piston head cavity.

M240B Machine GunM240B Machine GunPreventive MaintenancePreventive Maintenance

InspectionInspection

Inspection begins with the weapon disassembled into its Inspection begins with the weapon disassembled into its eight major assemblieseight major assemblies. Note that a shiny surface on a part . Note that a shiny surface on a part does not mean the parts are unserviceable. The gunner does not mean the parts are unserviceable. The gunner inspects each area of the weapon and related equipment inspects each area of the weapon and related equipment for the conditions indicated. Any broken or missing parts for the conditions indicated. Any broken or missing parts should be repaired or replaced.should be repaired or replaced.

The gunner should perform PMCS every 90 days. If the The gunner should perform PMCS every 90 days. If the weapon has not been used in 90 days, the PMCS in the weapon has not been used in 90 days, the PMCS in the operator's manual should be performed regardless. If you operator's manual should be performed regardless. If you see rust on a weapon, the PMCS should be done see rust on a weapon, the PMCS should be done immediately. Inspect all of the components for broken or immediately. Inspect all of the components for broken or missing parts. Inspect parts for cracks, dents, burrs missing parts. Inspect parts for cracks, dents, burrs excessive wear, rust, or corrosion. Inspect external excessive wear, rust, or corrosion. Inspect external surfaces for adequate finish.surfaces for adequate finish.

M240B Machine GunM240B Machine Gun Preventive MaintenancePreventive Maintenance


Barrel AssemblyBarrel Assembly

Check barrel for bulges, bends, burrs, Check barrel for bulges, bends, burrs, obstructions and obstructions or pits in the obstructions and obstructions or pits in the chamber or bore. Disassemble, inspect, and clean chamber or bore. Disassemble, inspect, and clean the gas collar and plug. Ensure the flash the gas collar and plug. Ensure the flash suppressor is fastened securely. Inspect the front suppressor is fastened securely. Inspect the front sight for damage or looseness. Inspect carrying sight for damage or looseness. Inspect carrying handle assembly for bent, broken, or missing handle assembly for bent, broken, or missing parts. Assure the heat shield is present, on the parts. Assure the heat shield is present, on the barrel assembly, and is not bent or broken, and barrel assembly, and is not bent or broken, and does not have any missing parts.does not have any missing parts.


InspectionInspection Buttstock and Buffer AssemblyButtstock and Buffer Assembly..

Check for burrs and rough edges on mating Check for burrs and rough edges on mating grooves and flanges. Check to be sure the back grooves and flanges. Check to be sure the back plate latch locks the buffer assembly securely to plate latch locks the buffer assembly securely to the receiver assembly when installed. Make sure the receiver assembly when installed. Make sure the buffer plug sticks out through the back plate the buffer plug sticks out through the back plate and is flush or higher than the protrusion below it. and is flush or higher than the protrusion below it. Make sure there is no rattling sound when the Make sure there is no rattling sound when the buffer is shaken and that the plug cannot rotated buffer is shaken and that the plug cannot rotated by finger pressure. Inspect the butt stock for by finger pressure. Inspect the butt stock for cracks. Check to make sure the back plate locks cracks. Check to make sure the back plate locks the butt stock securely to the receiver assembly the butt stock securely to the receiver assembly when installed.when installed.



Driving Spring Rod AssemblyDriving Spring Rod Assembly. Check the spring for broken . Check the spring for broken strands. Ensure the rod assembly is not bent.strands. Ensure the rod assembly is not bent.

Bolt And Operating Rod Assembly. Inspect entire area of the bolt and operating rod assembly for missing parts, broken or cracked areas, burrs, bends, or pits on the surface. Looking at the bolt, you can see if the firing pin is broken. The extractor should not move. The operating rod piston should have a slight movement from left to right (about 1/8-inch turn). When the bolt and operating rod are pulled to the rear, the piston should move freely without binding



Trigger Mechanism/Housing AssemblyTrigger Mechanism/Housing Assembly. Inspect . Inspect the tripping lever and sear for burrs on edges. the tripping lever and sear for burrs on edges. Push the tripping lever back to raise the sear, put Push the tripping lever back to raise the sear, put the safety on "S," and pull the trigger. The sear the safety on "S," and pull the trigger. The sear should not drop down far enough to lock in the should not drop down far enough to lock in the downward position. Place the safety on "F," and downward position. Place the safety on "F," and pull the trigger. The sear should drop down and pull the trigger. The sear should drop down and lock in the downward position. Check the sear lock in the downward position. Check the sear spring, ensuring the leg of the spring is behind the spring, ensuring the leg of the spring is behind the trigger pin and not between the trigger and the pin. trigger pin and not between the trigger and the pin. Check grip assembly for loose or missing grip Check grip assembly for loose or missing grip screws. Check trigger guard for bends or cracks. screws. Check trigger guard for bends or cracks. Check trigger spring pin for bends, and or broken Check trigger spring pin for bends, and or broken or missing spring.or missing spring.



Cover AssemblyCover Assembly. Pivot the feed lever back and forth to . Pivot the feed lever back and forth to ensure it operates smoothly without binding. Push in on ensure it operates smoothly without binding. Push in on the cover latches to make sure the retaining clip is not the cover latches to make sure the retaining clip is not

weak or missing and that they do not bind in the housing. weak or missing and that they do not bind in the housing. Push down on the cartridge guides and feed pawls to make Push down on the cartridge guides and feed pawls to make

sure the springs are not weak or missing. Inspect sure the springs are not weak or missing. Inspect accessory mounting rail for nicks or burrs.accessory mounting rail for nicks or burrs.

Feed TrayFeed Tray. Check for cracks, deformation, broken . Check for cracks, deformation, broken welds, or loose rivets.welds, or loose rivets.

HandguardHandguard. Check handguard for cracks, broken . Check handguard for cracks, broken or missing parts.or missing parts.



Receiver AssemblyReceiver Assembly. .

Check that the rear sight assembly is securely mounted Check that the rear sight assembly is securely mounted to the receiver and operates properly. Check that the to the receiver and operates properly. Check that the cocking handle operates the slide properly. Pull the cocking handle operates the slide properly. Pull the cocking handle to the rear and allow it to slowly return cocking handle to the rear and allow it to slowly return forward, making sure that the slide does not bind in the forward, making sure that the slide does not bind in the receiver. Check for damaged or missing ejection port receiver. Check for damaged or missing ejection port cover, spring, and pin. Lower and raise the bipod legs, cover, spring, and pin. Lower and raise the bipod legs, ensuring they move freely without binding. Check bipod ensuring they move freely without binding. Check bipod legs for cracks, or twisted or incomplete assembly. legs for cracks, or twisted or incomplete assembly. Check the exterior surface of the M240B for the exterior Check the exterior surface of the M240B for the exterior protective finish.protective finish.


InspectionInspectionMachine Gun.Machine Gun.

Assemble the weapon. Be sure parts are installed Assemble the weapon. Be sure parts are installed correctly and are in good working condition. correctly and are in good working condition. When installing the barrel, move the barrel When installing the barrel, move the barrel release slowly to the right and count the number release slowly to the right and count the number of clicks. Fewer than two and more than seven of clicks. Fewer than two and more than seven clicks indicate defective parts. Check both clicks indicate defective parts. Check both barrels. Check weapon functioning with belted barrels. Check weapon functioning with belted dummy ammunition by performing a function dummy ammunition by performing a function check. If weapon does not function properly and check. If weapon does not function properly and the cause cannot be determined using troubling the cause cannot be determined using troubling shooting procedures, notify direct-support shooting procedures, notify direct-support maintenance.maintenance.

M240B Machine GunM240B Machine GunT&E NomenclatureT&E Nomenclature

M122A1 Tripod

M240B Machine GunM240B Machine Gun T&E NomenclatureT&E Nomenclature

M240B Machine gun Mounted on Tripod and T&EM240B Machine gun Mounted on Tripod and T&E

1. Front receiver 1. Front receiver bushingbushing2. Pintle Assembly2. Pintle Assembly3. Quick release pin3. Quick release pin4. T & E Mechanism4. T & E Mechanism5. T & E Fork 5. T & E Fork AssemblyAssembly6. Spring Pin6. Spring Pin

M240B Machine GunM240B Machine Gun Operators Course Operators Course

Zero the T & E MechanismZero the T & E Mechanism Installation of Equipment (Tripod, Installation of Equipment (Tripod,

Pintle(s), T & EPintle(s), T & E

M240B Machine GunM240B Machine GunOperator CourseOperator Course

Blank Fire AttachmentBlank Fire Attachment

DO NOT FIRE BLANK AMMUNITION AT ANY PERSON WITHIN 20 FEET BECAUSE FRAGMENTS OF A CLOSURE WAD OR PARTICLES OF UNBURNED PROPELLANT CAN CAUSE DEATH.


Attach the BFAAttach the BFA. Unscrew the shaft (1) until it slides . Unscrew the shaft (1) until it slides all the way to the rear. Install the chamber device all the way to the rear. Install the chamber device (2) over the flash suppressor (3). Slide the shaft (2) over the flash suppressor (3). Slide the shaft (1) into the throat of the flash suppressor. Engage (1) into the throat of the flash suppressor. Engage the threads on shaft into the body of the chamber the threads on shaft into the body of the chamber device (2); turn clockwise until it is hand tight.device (2); turn clockwise until it is hand tight.


Remove the BFARemove the BFA. Hold the barrel and rotate . Hold the barrel and rotate the chamber of the body (2) about 180 degrees the chamber of the body (2) about 180 degrees counterclockwise to break any carbon sealed counterclockwise to break any carbon sealed between the shaft (1) and the suppressor (3). between the shaft (1) and the suppressor (3). Unscrew the shaft (1) until the threads Unscrew the shaft (1) until the threads disengage. Remove the chamber device from disengage. Remove the chamber device from the suppressor (3).the suppressor (3).


DESTRUCTIONDESTRUCTION

Destruction of any military weapon is only Destruction of any military weapon is only authorized as a last resort to prevent enemy authorized as a last resort to prevent enemy capture or use. This paragraph discusses the capture or use. This paragraph discusses the field-expedient means of this destruction; it field-expedient means of this destruction; it does not replace published policies. In does not replace published policies. In combat situations, the commander has the combat situations, the commander has the authority to destroy weapons, but he must authority to destroy weapons, but he must report this destruction through channels.report this destruction through channels.


DESTRUCTIONDESTRUCTION

a. Disassemble the weapon as completely as time a. Disassemble the weapon as completely as time permits. Use the barrel or tripod mount to destroy permits. Use the barrel or tripod mount to destroy the bolt and operating rod assembly, barrels, rear the bolt and operating rod assembly, barrels, rear and front sights, and mounts.and front sights, and mounts.

b. Bury the disassembled weapon or dump the b. Bury the disassembled weapon or dump the parts into a stream, a sump, or a latrine.parts into a stream, a sump, or a latrine.

c. Burn the weapon by placing an incendiary c. Burn the weapon by placing an incendiary grenade on the receiver group over the bolt (with grenade on the receiver group over the bolt (with the cover resting on the grenade) and detonating the cover resting on the grenade) and detonating the grenade.the grenade.

d. Smash the traversing and elevating mechanism d. Smash the traversing and elevating mechanism and pintle assembly. Bend the tripod legs.and pintle assembly. Bend the tripod legs.


MOUNTING THE NIGHT SIGHTMOUNTING THE NIGHT SIGHT

VEHICULAR MOUNTSVEHICULAR MOUNTS


TECHNIQUES OF FIRE AND EMPLOYMENTTECHNIQUES OF FIRE AND EMPLOYMENTRoles of the Machine gunRoles of the Machine gun

1. Supports rifleman in offensive and defensive 1. Supports rifleman in offensive and defensive modemode

2. Provides heavy volume of close and continuous 2. Provides heavy volume of close and continuous fire.fire.

3. Can engage target beyond the capability of 3. Can engage target beyond the capability of rifleman.rifleman.

4. Marking or locating target.4. Marking or locating target.5. Aerial defense when necessary.5. Aerial defense when necessary.


CHARACTERISTICS OF FIRECHARACTERISTICS OF FIRE

Trajectory and maximum ordinate.Trajectory and maximum ordinate.TrajectoryTrajectory- path of projectile.- path of projectile.Almost flat at 300 meters or less, beyond 300 Almost flat at 300 meters or less, beyond 300 meters trajectory is curved and becomes meters trajectory is curved and becomes greater as range increases.greater as range increases.Maximum ordinateMaximum ordinate- Highest point trajectory - Highest point trajectory reaches from muzzle to target.reaches from muzzle to target.Occurs at 2/3 of distance between gun and Occurs at 2/3 of distance between gun and target.target.


CONE OF FIRE AND BEATEN ZONECONE OF FIRE AND BEATEN ZONE

Cone of FireCone of Fire-- Patter formed by several Patter formed by several rounds in a burst, each round taking rounds in a burst, each round taking a slightly different trajectory.a slightly different trajectory.

Primary cause: vibration of gunPrimary cause: vibration of gun

Other causes: Variations in Other causes: Variations in ammunition, and atmospheric ammunition, and atmospheric conditions. conditions.


BEATEN ZONEBEATEN ZONE- Area where cone of fire strikes the - Area where cone of fire strikes the ground.ground.

Will change when range to target changes.Will change when range to target changes.

On uniformly sloping or level terrain, the beaten zone On uniformly sloping or level terrain, the beaten zone is long and narrow.is long and narrow.

As range increases beaten zone becomes shorter and As range increases beaten zone becomes shorter and wider.wider.

With terrain sloping down and away from the gun, the With terrain sloping down and away from the gun, the beaten zone becomes longer.beaten zone becomes longer.

With terrain rising, the beaten zone becomes shorterWith terrain rising, the beaten zone becomes shorter

Terrain has no great effect on the width of the beaten Terrain has no great effect on the width of the beaten zone.zone.


Danger SpaceDanger Space – Space between gun and target where – Space between gun and target where trajectory does not rise above 1.8 meters.trajectory does not rise above 1.8 meters.

Fired over level or uniformly sloping terrain: Fired over level or uniformly sloping terrain:

Over 700 meters trajectory will rise over 1.8 meters.Over 700 meters trajectory will rise over 1.8 meters.

Some areas between gun and target may not have Some areas between gun and target may not have danger space.danger space.

Dead SpaceDead Space- area that can’t be seen or covered by gun - area that can’t be seen or covered by gun position. Caused by depression, rises, obstructions, position. Caused by depression, rises, obstructions, etc. etc.

M240B Machine GunM240B Machine GunOperator CourseOperator CourseCLASSES OF FIRECLASSES OF FIRE

Respect to groundRespect to ground: :

1. 1. GrazingGrazing- Center of cone of fire does not rise - Center of cone of fire does not rise above 1 meter above the ground. above 1 meter above the ground.

Maximum extent of fire over level of Maximum extent of fire over level of uniformly sloping terrain is 600 metersuniformly sloping terrain is 600 meters

2. 2. PlungingPlunging- Danger space is practically - Danger space is practically confined to beaten zoneconfined to beaten zone

Obtaining Plunging Fire-Obtaining Plunging Fire-

Target range greater than 600 meters.Target range greater than 600 meters.

Fire from high to low ground.Fire from high to low ground.

Fire into abruptly rising ground.Fire into abruptly rising ground.

M240B Machine GunM240B Machine GunOperator CourseOperator Course CLASSES OF FIRECLASSES OF FIRE

Respect to Respect to Target:Target:

1. Frontal- firing directly into front of target, 1. Frontal- firing directly into front of target, long axis of the beaten is at right angle to long axis of the beaten is at right angle to front of target.front of target.

2. Flanking- firing directly against flank (right 2. Flanking- firing directly against flank (right angle) of target.angle) of target.

3. Oblique- firing at an angle other a right angle 3. Oblique- firing at an angle other a right angle to target.to target.

4. Enfilade- long axis of beaten zone may or 4. Enfilade- long axis of beaten zone may or may not coincide with long axis of target.may not coincide with long axis of target.

M240B Machine GunM240B Machine GunOperator CourseOperator Course CLASSES OF FIRECLASSES OF FIRE

Respect to Respect to gun:gun:

1. Fixed- firing at a stationary target which the beaten 1. Fixed- firing at a stationary target which the beaten zone covers target.zone covers target.

2. Traversing- firing distributed in width by successive 2. Traversing- firing distributed in width by successive changes in direction.changes in direction.

3. Searching- firing distributed in depth by successive 3. Searching- firing distributed in depth by successive changes in elevation.changes in elevation.

4. Traversing and searching- amount of adjustment is 4. Traversing and searching- amount of adjustment is determined by slope of terrain and angle of target.determined by slope of terrain and angle of target.

5. Free gun- fire delivered against massive targets.5. Free gun- fire delivered against massive targets.


Range Determination and Range Determination and Lateral Distance MeasurementLateral Distance Measurement

Uses.Uses.

1. Accurate determination affects gunner’s marksmanship 1. Accurate determination affects gunner’s marksmanship abilities.abilities.

2. Is required in reporting of information and the 2. Is required in reporting of information and the adjustment of artillery and mortar fireadjustment of artillery and mortar fire

Methods.Methods.

1. 100 meter unit-of-measure1. 100 meter unit-of-measure

2. Pacing- 115 paces approx. 100 meters2. Pacing- 115 paces approx. 100 meters

3. Appearance of objects- Most common method used.3. Appearance of objects- Most common method used.

4. T & E method.4. T & E method.


Principles of FirePrinciples of Fire

Types of targetsTypes of targets

1. Point targets- require single aiming points.1. Point targets- require single aiming points.

2. Area targets- having considerable width 2. Area targets- having considerable width and depth.and depth.

Rates of fireRates of fire

Sustained- 100 rpm, barrel change (10 Min.)Sustained- 100 rpm, barrel change (10 Min.)

Rapid- 200 rpm, barrel change (2 Min.)Rapid- 200 rpm, barrel change (2 Min.)

Cyclic- 550 rpm, barrel change every minuteCyclic- 550 rpm, barrel change every minute


Engagement of visible targetsEngagement of visible targetsEngagement of targets during limited Engagement of targets during limited

visibilityvisibilityPredetermined firesPredetermined fires

Range CardsRange CardsNight vision sightNight vision sight

Zeroing PVS-4 night vision sightZeroing PVS-4 night vision sightEstimating range sighting and aimingEstimating range sighting and aiming


PREPARATORY MARKSMANSHIP TRAININGPREPARATORY MARKSMANSHIP TRAINING

1. 1. Firing positions-Firing positions- gunner gets into prone position gunner gets into prone position behind gun right shoulder and right hip pocket behind gun right shoulder and right hip pocket should be directly behind gun. Spread legs with should be directly behind gun. Spread legs with heels down.heels down.

2. 2. Grip- BipodGrip- Bipod Right hand on grip and index finger on trigger.Right hand on grip and index finger on trigger. Left palm down on cover.Left palm down on cover. Both hands firmly pressed down and rearward.Both hands firmly pressed down and rearward.3. 3. TripodTripod - Right hand on grip and index finger on - Right hand on grip and index finger on

trigger. trigger. Left hand on T & E Left hand on T & E


AimingAimingSight AlignmentSight Alignment

Sight PictureSight PictureTrigger ManipulationTrigger Manipulation

Pull do not squeeze triggerPull do not squeeze triggerSight AdjustmentSight Adjustment

Windage knob- one click equals 1 milWindage knob- one click equals 1 milPush forward – strike moves rightPush forward – strike moves right

Pull back- strike moves leftPull back- strike moves left


Sight Adjustment continuedSight Adjustment continued

Elevation knob- four clicks equals 1 milElevation knob- four clicks equals 1 mil

Turn left- strike moves upTurn left- strike moves up

Turn right- strike moves downTurn right- strike moves down

Adjusted Aiming PointAdjusted Aiming Point

Rapid/accurate adjustment without adjusting Rapid/accurate adjustment without adjusting sights sights


Target AnalysisTarget Analysis

Chemical Warfare Defense Ensemble Chemical Warfare Defense Ensemble (CWDE)(CWDE)

Firing from VehiclesFiring from Vehicles


PERFORMANCE EVALUATIONPERFORMANCE EVALUATION

GO/NO GO CHECKLISTSGO/NO GO CHECKLISTS

LIVE FIRELIVE FIRE

PRACTICE PHASE/EVALUATIONPRACTICE PHASE/EVALUATION

m240b machine gun operators course. overviewi orientation and mechanical training ii techniques of...

Documents

sure machine gun

runaway machine gun

maintenance slide

chamber slide

practice evaluation

barrel assembly

hot barrel

quick barrel changes