breechblock

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Related to breechblocks: breech mechanism

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 ?
At the rearmost point of movement, the breechblock was held to the rear while the barrel, powered now by the compressed recoil spring, was pushed forward and back into the original position.
The better of the two, the one I bought from my buddy, had a broken breechblock.
I think it was due to the design of the cuts for the locking bolt in the breechblock as well as the heat treat and metal used at that time.
Clearing the chamber was effected by opening the breechblock and pulling it rearward to extract the spent case.