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A breechblock (or "breech block") is the part of the firearm action that closes the breech of a weapon (whether small arms or artillery) at the moment of firing.

Most modern small firearms use a bolt. Some variations of breechblocks include:

A less common type of breech is the split-breech design known as the "nutcracker". This type of breech consists of two counter-rotating sprockets, with a temporary breech being formed where they touch. Relatively few guns have used this design. The prototype Fokker-Leimberger multiple-barreled machine gun used this design, but it had numerous problems with ruptured cases.[1] Another "Fokker Split Breech Rotary Machine Gun, ca. 1930" was donated to Kentucky Military Treasures; according to the museum record it "proved unsuccessful because of its inability to seal breech cylinders".[2][3] A couple of 1920s US patents by other inventors also proposed to use this principle.[4][5] The British also experimented with the design in the 1950s for aircraft guns, without success.[6] It has only been used successfully in low-pressure applications, such as the Mk 18 Mod 0 grenade launcher.[7]

In artillery the forces are much greater, but similar methods are used. The Welin breech block uses 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.

See also


  1. Пулемёт Fokker-Leimberger (Германия),
  6. Anthony G. Williams; Emmanuel Gustin (2005). Flying Guns of the Modern Era. Crowood. p. 55. ISBN 978-1-86126-655-2. 
  7. Anthony G Williams (8 November 2005), SPLIT BREECH GUNS: THE NUTCRACKER AND THE 40MM MK 18

External links

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