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 ?
HISTORIC MAKER: Ithaca Gun Company, Ithaca, New York ACTION TYPE: Peabody, pivoting breechblock with rebounding hammer, CALIBER: .
That lets the breechblock close firmly, but the constant pressure wears out the springs and leads to early failure.
If the NBC system is not operating, you must wait 30 minutes before opening the breechblock.
The winner of the trials was a rifle that used a dropping block action designed by Henry Peabody of Boston and modified by the Swiss engineer Friederich von Martini, with a spring loaded striker/firing pin assembly inside the breechblock and used a separate lever to lower the breechblock.
The rear inside of the action body was cut with a sloping opening into which a correspondingly angled lug on the rear of the breechblock nestled when the lever was closed.
To control combustion leakage at the breech, Starr milled an angled, annular groove in the face of the breechblock, which mated with and closed over the similarly shaped end of the barrel, forming a tight, almost gas-proof joint.
Mechanics, the tank's breechblock plunger tool, shown as Fig 9 in App D of TM 9-2350-388-20-2-4, has been modified to make your job a little easier.
The improved version utilized a recoil-operated locking system with a hinged bolt that is patterned after the lever-action Peabody Martini breechblock.
45-110 can't fit in them because they hang up on the breechblock.
When the tank fires, the breechblock doesn't drop to allow the aft cap to be ejected from the chamber.
The slide of the breechblock slams rearward at a velocity of about 45 miles per hour.