breechblock

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breechblock

[′brēch‚bläk]
(ordnance)
A movable steel block in the mechanism of a breech-loading gun that seals the breech opening of the barrel during firing.
References in periodicals archive ?
These mate with the rear of the breech block when firing the rifle and lock the block shut.
The number is actually on the flat surface on top of the breech block lug, near where the hinge pin is located.
With the breech block in the locked position, the primer is protected from rain and snow, and the design also permits easy access to the primer pocket.
Without much attention called to the change, the breech block eventually incorporated a solid stainless steel pin.
The breech block is part of the M119A2's cannon assembly, along with the muzzle brake, cannon tube and breech.
The other nice touch to the newer design is a 3-position shell deflector just aft of the breech block. The shell deflector can be turned to flick ejected brass to the right or left of the shooter or when centered to stop and catch the empty case if the rifle were chambered for a centerfire caliber, and the shooter wanted to save his brass.
I am a new gunsmith and I have a old Browning Auto-5 (serial number 46808) with a locked up breech block and I can't get the barrel off.
The firing-pin and firing-pin spring were retained by the screw-in bushing and the bushing was pinned into the breech block to keep it from turning out.
Change all coax ammo feed chute references in Step 4 to breech block.
It is a lever action falling breech block action in 12 gauge with a 2.75 inch chamber, 19 inch barrel length with modified choke and a magazine capacity of five rounds.