FM 23-45 Basic Field Manual
18
held raised, as the sear moves forward with the bolt the trigger cams engage the sear
cams and force the sear down, releasing the firing pin. The gun thus fires
automatically, repeating the operations of functioning already described. The release of
the firing pin actually takes place about 1/16 inch before the recoiling parts reach the
forward position but after the breech is locked.
S
ECTION V
STOPPAGES AND IMMEDIATE ACTION
■40. DEFINITIONS.—
a
. A "stoppage" is any unintentional cessation of fire.
b
. "Immediate action" is the procedure used for the prompt reduction of usual
stoppages.
■41. STOPPAGES.—
a
. Prevention.—Stoppages will be reduced to the minimum if the gunner has a
practical working knowledge of his weapon and applies the points which should be
observed before firing Prevention is the best remedy for all stoppages.
b
. Causes.—
(1) A stoppage will occur if the gun fails to feed, fails to load, or fails to fire.
(
a
) If the gun fails to feed, the cause for the stoppage will be found in the
ammunition belt or in the feed mechanism.
(
b
) If the gun feeds but falls to load, the cause will be found in the receiver. A
broken part or an obstruction on the T-slot or in the chamber is the usual cause.
(c) If the gun feeds and loads but fails to fire, the cause will be found in the
firing mechanism unless the primer of the cartridge is defective.
(2) The table following includes a comprehensive list of possible stoppages. It will
serve as a guide during instruction in stoppages or immediate action.
TABLE OF STOPPAGES
Stoppages Method of preparing for instruction in
immediate action and stoppages
1. Misfire due to defective primer. 1. Place a dummy cartridge in belt.
2. Short round. 2. Place a short round in belt.
3. Bulged round. 3. Insert bulged round in belt.
4. Tight loop in belt.
1
4. Do not prepare
5. Empty loop in belt. 5. Leave an empty loop in belt.
6. Stretched or torn belt.
1
6. Do not prepare.
7. Thin rim, permitting nose of bullet to
drop below chamber.
1
7. Do not prepare
8. Belt improperly loaded. 8. Pull cartridge partially out of belt
9. Battered or thick rim of cartridge. 9. Place a battered or thick rimmed
cartridge in belt.
10. Failure to remove round from
chamber
10. Place a dummy cartridge with rim
filed off in the chamber.
11. Set back primer.
1
11. Do not prepare.
12. Separated case which is removed
from chamber by new round when
bolt is pulled to the rear.
12. Drive the front portion of a
cartridge securely on a dummy
cartridge. Pull bolt to the rear and
place cartridge properly on the face
