A breechblock (or "breech block") is the part of the
firearm actionthat closes the breech of a weapon (whether small arms or artillery) at the moment of firing.
Most modern small firearms use a rotating breechblock, better known as a bolt, first used in manually operated
bolt actionweapons, but later operated by the power of the cartridge in automatic weapons. Some variations of non-rotating breechblocks include:
*Blowback - in which the breechblock is closed by a powerful spring. A variation of this is the "Delayed blowback" found in many weapons from
Heckler & Koch
*Tipping breechblocks - both self-actuating (
AG-42Ljungman is one example) and manually operated by a lever ( Peabody action) or other means ( Krag-Petersson)
*Falling block (
*Side-hinged breechblock (
*Front-hinged breechblock (Springfield)
*Screw breechblock (
*Rotating crank (
Colt revolving rifle)
In artillery the forces are much greater, but similar methods are used. The
Welin breech blockuses an interrupted screw and is used on weapons with calibres from about 4 inches up to 16 inches or more. Other systems use horizontal or vertical sliding block.
The "Latched breechblock" hasn't existed historically, but is a possible breechblock. The principle of the "latched breechblock" is that the breech is closed by putting a cap, and a cap is locked by latch.
* [http://riv.co.nz/rnza/hist/ord/breech.htm Breech Mechanisms in artillery]
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