LUMP

One of several projections located on the underside of the barrel or barrels on break action guns, which serves to secure the barrels to the action or receiver. See Barrel Lug.

LOCK ENERGY

The amount of energy delivered to the primer from the firing-pin blow.

LOCK FRAME

A device incorporated into the mechanism of some firearms where the barrel and the bolt assembly recoil upon firing. The lock frame acts to absorb the shock of the recoiling parts prior to the bolt unlocking and opening.

LOCK PLATE

A metal plate mounted on the stock of a gun to provide for mounting of, or access to, the firing mechanism.

LOCKED BREECH ACTION

An action in which the breech bolt is locked to the barrel or receiver, until unlocked through a mechanical process.

LOCKING BLOCK

The firearm component designed to secure the action in the locked position.

LOCKING CAM

An incline, either helical or straight, to assist in closing the action on a chambered cartridge.

LOCK-TIME

The time interval between sear release and the firing-pin striking the primer.

LONG RIFLE

1. Originally, the term was used in reference to long-barreled flintlock rifles. 2. The name given one type of a caliber 22 rimfire cartridge.