Misfire, Hangfire, and Cookoff

TM 9-6920-361-13&P

c. Extraction. Pull the bolt to the rear to eject

the cartridge case. If the case fails to extract, use the

cleaning rod to remove it; then follow instructions in table

3-2. If the adapter is installed in the breech recess of the

major caliber weapon (e.g., 105-mm howitzer M102) it

will have to be removed from the tube in order to push

the cartridge case out with the cleaning rod. If the

adapter is installed in place of the obturator spindle (e.g.,

155-mm howitzer M114A1), it is only necessary to open

the breechblock of the major caliber weapon.

Misfire, Hangfire, and Cookoff

(1) Misfire. A misfire is a complete failure

to fire and may be due to a faulty firing mechanism or

faulty element in the propelling charge explosive train. A

misfire in itself is not dangerous, but since it cannot be

immediately distinguished from a delay in the functioning

of the firing mechanism or from a hangfire, these

possibilities should be considered until they have been

eliminated. Such delay in the functioning of the firing

mechanism could result from the presence of foreign

matter such as sand, grit, frost, and ice, or improper or

excessive oil or grease. These conditions might create a

partial mechanical restraint which, after some delay, is

overcome as a result of the continued force applied by

the spring, and the firing pin then driven into the primer in

the normal manner. No cartridge should be left in a hot

trainer or subcaliber device any longer than

circumstances require because of the possibility of a

cookoff.

(2) Hangfire. A hangfire is a delay in the

functioning of a propelling charge at the time of firing.

The amount of delay is unpredictable but, in most cases,

will fall within the range of a split second to several

minutes. A hangfire cannot immediately be distinguished

from a misfire, and, therefore, it may be mistaken for a

Figure 2-19. Misfire device

misfire. In case of a misfire, perform the following steps

NOTE

in sequence:

You may have a hangfire. A hangfire

(a) Keep the device trained on the

cannot be distinguished from a

target and all personnel clear of the muzzle.

(b) Before attempting to remove the

misfire if the firing pin has been

cartridge from the trainer, personnel not required for the

released. If the firing pin has not

operation will be cleared from the vicinity.

been released you can immediately

proceed to steps d, e, and f.

the firing pin has been released and is forward. (It will

protrude from the rear of the bolt if the weapon is

(d) Attach locally fabricated device,

cocked). If the firing pin has been released, wait 30

(figure 2-19) to breech bolt lever.

seconds and proceed with steps d, e, and f.

(e) Pull bolt lever up, then to the rear

and eject cartridge.

(f) Inspect the cartridge from a

distance to determine if the cartridge or firing mechanism

is at fault. If the primer is dented, dispose of the

cartridge in accordance with local regulations for small

arms ammunition. If primer is not dented, disassemble

the bolt and repair as necessary.

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