Breechblock
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.
Variants
Most modern small firearms use a bolt. Some variations of breechblocks include:
- Blowback actions – in which the breech is never locked and is held closed by spring tension alone.
- rotating bolt – the bolt rotates to lock into the breech
- Tilting breechblock – both self-actuating (AG-42 Ljungman is one example) and manually operated by a lever (Peabody action).
- Falling block – (Sharps rifle)
- Floating breech
- Rolling block – (Remington)
- Hinged breechblock – (Snider-Enfield, Springfield rifle)
- Screwed breechblock (Ferguson rifle)
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 a horizontal or vertical sliding block, in which a solid block is slid across the open breech from the side or bottom to seal the opening.
See also
- Category:Firearm actions
References
- ↑ Пулемёт Fokker-Leimberger (Германия), www.dogswar.ru/oryjeinaia-ekzotika/strelkovoe-oryjie/6274-pylemet-fokker-leimb.html
- ↑ http://www.lrc.ky.gov/record/Moments10RS/web/KMT%20legislative%20moment%2040.pdf
- ↑ http://kyhistory.pastperfect-online.com/35577cgi/mweb.exe?request=record&id=B54DA4F4-8851-4F4D-ADC2-453181649430&type=101
- ↑ http://www.google.com/patents/US1328230
- ↑ http://www.google.com/patents/US1399119
- ↑ Anthony G. Williams; Emmanuel Gustin (2005). Flying Guns of the Modern Era. Crowood. p. 55. ISBN 978-1-86126-655-2.
- ↑ Anthony G Williams (8 November 2005), SPLIT BREECH GUNS: THE NUTCRACKER AND THE 40MM MK 18