View Full Version : Ident: Definitions of parts and/or techniques

December 22, 2000, 12:34
I've been looking for definitions of these terms for a little while and am having no luck. Could someone please tell me what is:

1) sear
2) carrier
3) lapping
4) breech
5) breech face
6) locking shoulder

This may keep my head from exploding while reading technical stuff about my FAL.

Super B
December 22, 2000, 13:32
The sear is the part that connects the trigger to the hammer. Without the sear, pulling the trigger would have no effect.

The bolt carrier is a housing that protects and adds mass to the bolt. The bolt engages the receiver to lock the action closed until pressures are low enough to safely eject the spent shell casing.

Lapping is a term that means slowly polishing something until it fits perfectly with another part. Sanding or grinding would remove too much metal, so you lap the parts until they fit.

The breech and breech face refer to the front part of the receiver, where the barrel protrudes. The wear marks you see on the front of the bolt carrier are caused by the carrier impacting the breech face.

The locking shoulder is a piece of metal that is square in cross section that sticks through your receiver about halfway back. The square cut across the back lower part of the bolt rest on the locking shoulder when the gun is in battery. The locking shoulder is made if very hard metal. If you put in a larger locking shoulder, you force the bolt closer to the breech face and tighten the headspace. Conversly, if you put in a smaller locking shoulder, you allow the bolt to movr farther back when the bolt is locked and ready to fire. This loosens the headspace. This is the way you adjust the headspace in a FAL.

Super B

December 22, 2000, 15:18
Bless you.