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 ?
After the shot has been fired and the trigger released, the breech block is retracted, the cylinder is moved back into position by the compressed bushing spring, and the cycle is ready to begin again.
The number is actually on the flat surface on top of the breech block lug, near where the hinge pin is located.
All these over-and-under derringers have steel breech block inserts, steel barrels, and steel striker-type firing mechanisms.
Tenders are invited for Slider Breech Block Drg No.
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.
22 Magnum derringer-style pistol (two shots) with a drop-in breech block in both calibers, polymer-framed.
Change all coax ammo feed chute references in Step 4 to breech block.