Inspection And Destruction


34. General

A stoppage is any interruption in the cycle of operation caused by the faulty action of the gun or ammunition. The first thing: to do when a stoppage occurs is to apply immediate action. Immediate action is the prompt action taken by the firer to reduce a stoppage (para 86).

35. Types of Stoppage*

a. General. Stoppages are classified as follows:

(1) Failure to feed: A stoppage that prevents the round from being properly position«! in the receiver group.

(2) Failure to chamber: A stpppage that prevents the chambering of the round completely.

(8) Failure to lock: A stoppage that prevents the breech lock from correctly entering its recess in the bolt

(4) Failure to fire: A stoppage that prevents the ignition of the round.

(5) Failure to unlock: A stoppage that prevents the breech lock from moving out of its recess in the bolt.

(6) Failure to extract: A stoppage that prevents the extraction of the expended cartridge from the chamber.

(7) Failure to eject: A stoppage that prevents the ejection of the expended cartridge from the receiver.

(8) Failure to cock: A stoppage that prevents the firing pin extension from being engaged with the sear.

b. Common Stoppages. The most common stoppages with caliber .50 HB, M2 machineguns are:

(1) Failure to feed.

(2) Failure to chamber.

o. Causes of Stoppages. The chart below lists the usual, and other causes of the various stoppages.

Nttu* oi atoppat«



Failure to feed.

Failure to chamber. Failure to lock

Failure to unlock.

Failure to extract. Failure to eject... Failure to cock___

Defective ammunition belt

Defective feed mechanism.

Defective extractor

Broken pert or obstruction In T-ilot or chamber. Separated (ruptured) case. Incorrect headspace

Defective parte in firing machanlsm. Defective ammunition. Incorrect timing. Broken parte in receiver

Dirty chamber

Defective ejector

Broken eear

Worn eear notch. Weak sear apring.

Worn hooked notch on firing pin extension.

Improperly Loaded belt. Short round.

Thick or thin rimf bulged round, set back primer. Broken parte. Battered breech lock. Barrel breech lock cam. Faulty breech lock cam adjustment.

Worn or faulty breech lock cam, or adjustment. Defective cartridge case. Burred T-ilot. Broken cocking lever.

d. Malfunctions. A malfunction is any failure of the gun to function satisfactorily.

(1) Failure to function freely. Sluggish operation is usually due to human failure to eliminate excessive friction caused by dirt, lack of proper lubrication, burred parts, tight headspace adjustment, or incorrect timing.

(2) Uncontrolled automatic fire. Uncontrolled automatic fire is continued Are when the trigger or trigger control mechanism is released. If the cause is present before the gun is fired, the gun will start to fire when the recoiling groups move into battery the second time. If the defect occurs during firing, the gun will continue firing when the trigger control mechanism is released.

(a) Uncontrolled automatic fire {runaway gun) may be caused by the following:

1. Bent trigger lever, forward end of the trigger lever sprung downward.

2. Burred beveled contacting aurfacet-of the trigger lever and sear.

J. Jammed or broken sideplate trigger.

(b) To remedy uncontrolled automatic fire:

1. Keep the gun laid on target.

2. Twist the belt, causing the gun to jam.

Note. This may damage the feeding mechanism.


8. Replace broken, worn, or burred parts. Check the Bideplate trigger and trigger con-trol mechanism, when applicable.


36. General a. Immediate action is performed by the gunner; however, every crew member must be trained to apply immediate action. The procedures outlined below will assist in reducing most stoppages without analyzing their cause in detail.

b. If gun fails to fire:

(1) Wait 5 seconds; a hangfire may be causing the misfire. In the next 5 seconds, pull the bolt to the rear (check for ejection and feeding of belt), release it, relay on the target and attempt to fire.

Not*. When the bolt latch engages the holt and holds it to the rear, the gunner must return the retracting elide handle to ite forward poiltion. If the boltlatch release and trigger are depressed at the same time, the bolt goes forward and the weapon should fire automatically.

(2) If the gun again fails to fire, wait 5 seconds, pull the bolt to the rear (engage with bolt latch if applicable) and return the retracting slide handle to its forward position. Open the cover and remove the belted ammunition. Inspect the gun to determine the cause of stoppage as outlined in paragraph 86c.

37. Safety Precaution» After Misfire

A hangfire or cookoff can cause injury to personnel or damage to the weapon. To avoid these, the gunner must take the following precautions:

a. Always keep the round locked in the chamber the first 5 seconds after a misfire occurs. This prevents an explosion outside of the gun in event of a hangfire.

b. If the barrel is hot, the round must be extracted within the next 5 seconds to prevent a cookoff. When more than 160 rounds have been fired in a 2-minute period, the barrel is hot enough to produce a cookoff.

c. If the barrel is hot and the round cannot be extracted within the 10 seconds, it must remain locked in the chamber for at least 5 minutes, to guard against a cookoff.

d. The gun cover unit remain closed during the waiting periods prescribed in a, b, and c above.

38. Reduction of Stoppages

When immediate action does not correct the malfunction, the quickest way to resume firing is to replace the defective part.

a. Removal of a Cartridge From the T-Slot. If the cartridge does not fall out, hold the bolt to the rear, and with the extractor raised, use a screwdriver to push the cartridge out the bottom of the receiver.

b. Removal of a Ruptured Cartridge. A ruptured (separated) cartridge case may be removed with a cleaning rod or ruptured cartridge extractor.

(1) To remove a ruptured cartridge with the ruptured cartridge extractor (cal .60 41-E-557-60, (7160041) raise the cover, and pull the bolt to the rear. Place the ruptured cartridge extractor in the T-slot of the bolt, in the same manner as that of a cartridge, so that it Is held in line with the bore by the ejector of the extractor assembly of the gun. With the ruptured cartridge extractor alined with the bore and held firmly in the T-slot, let the bolt go forward into battery. This forces the extractor through the ruptured case, and the shoulders will spring out in front of the case. Pull the bolt to the rear and ago uua

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