This chapter discusses the malfunctions, stoppages, immediate actions, remedial actions, and destruction procedures of the MG. All corrective actions must comply with safety procedures.
A malfunction is any failure of the gun to function satisfactorily. Examples of malfunctions are:
a. 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, incorrect headspace adjustment, or incorrect timing.
b. Uncontrolled Automatic Fire. Uncontrolled automatic fire (runaway gun) is when fire continues even 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 runaway gun may be caused -
• By a bent trigger lever, forward end of the trigger lever sprung downward.
• By burred beveled contacting surfaces of the trigger lever and sear.
• By a jammed or broken sideplate trigger.
To stop the uncontrolled automatic fire:
(1) Keep the gun laid on target.
(2) Twist the belt, causing the gun to jam.
(3) Caution, do not unlatch the cover.
(4) Wait 5 minutes to guard against cook off.
(5) Clear weapon, replace broken, worn, or burred parts. Check the sideplate trigger and trigger control mechanism, when applicable.
A stoppage is any interruption in the cycle of operation caused by the faulty action of the gun or ammunition. Stoppages are classified as follows:
a. Failure to Feed. Prevents the round from being properly positioned in the receiver group.
b. Failure to Chamber. Prevents the complete chambering of the round.
c. Failure to Lock. Prevents the breech lock from correctly entering its recess in the bolt.
d. Failure to Fire. Prevents the ignition of the round.
e. Failure to Unlock. Prevents the breech lock from moving out of its recess in the bolt.
f. Failure to Extract. Prevents the extraction of the expended cartridge from the chamber.
g. Failure to Eject. Prevents the ejection of the expended cartridge from the receiver.
h. Failure to Cock. Prevents the firing pin extension from being engaged with the sear.
Table 4-1 lists the causes of most stoppages.
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