Engineering:Tilting bolt

From HandWiki
Short description: Locking mechanism used in self-reloading firearms and straight-pull repeating rifles
M1895 Lee Navy with an open bolt, demonstrating its vertical locking surface on its bottom in front of the handle

Tilting bolt action is a type of locking mechanism often used in self-loading firearms and, rarely, in straight-pull repeating rifles. Essentially, the design consists of a moving bolt driven by some mechanism, most often a piston with gas pressure from the gas port behind the muzzle. The bolt drops down into receiver recess and locks on bolt closing. Tilting the bolt up and down locks-unlocks in the breech. This tilting allows gas pressure in the barrel from firing the gun to lower to safe levels before the cartridge case is ejected.

For handgun design, the tilting barrel as used in the Browning, is a similar operating mechanism. The tilting bolt has lost favor in contemporary firearm design of rifle caliber to locking systems such as the rotating bolt due to reasons such as increased wearing of the surfaces acted on, higher demands on the receiver due to transfer of locking stresses to it (e. g., it can't be made from aluminium or stamped sheet steel) & better potential accuracy of rotating bolt. Yet it is widespread in vintage firearms listed below.[1][2][3][4]

Examples

  • FN Model 1949, semi-automatic rifle
  • FN FAL, select-fire battle rifle
  • SKS, semi-automatic carbine
  • SVT-40, semi-automatic rifle
  • Kbsp wz. 1938M, prototype semi-automatic rifle
  • AS-44, prototype select-fire assault rifle
  • ZH-29, semi-automatic rifle
  • vz. 52 rifle, semi-automatic rifle
  • MAS-49, semi-automatic rifle
  • PTRS-41, semi-automatic anti-tank rifle
  • StG 44 & MKb 42(H), select-fire assault rifle
  • Ag m/42, semi-automatic rifle
  • ZB vz. 26, light machine gun
  • Bren light machine gun, light machine gun
  • Uk vz. 59, general purpose machine gun
  • M50 Reising, submachine gun; uniquely tilts upwards to lock and uses Delayed Blowback for action.
  • LS-26, light machine gun; uniquely uses Delayed Blowback for action.
  • Savage Model 99, lever action rifle
  • SK-46, prototype semi-automatic rifle
  • SIG Model U, prototype semi-automatic rifle
  • CZ-38, prototype semi-automatic rifle

See also

References

  1. "How a Tilting Bolt Works - YouTube". M.youtube.com. 2010-11-04. https://m.youtube.com/watch?v=8oqEGnSW-NQ. Retrieved 2018-04-15. 
  2. "L1A1 converts to full auto.wmv - YouTube". M.youtube.com. 2011-02-20. https://m.youtube.com/watch?v=7liLHMXlViE. Retrieved 2018-04-15. 
  3. Nathaniel F (2016-06-22). "Operating Systems 201: Tilting Bolt Locking - The Firearm BlogThe Firearm Blog". Thefirearmblog.com. http://www.thefirearmblog.com/blog/2016/06/22/operating-mechanisms-201-tilting-bolt-locking/. Retrieved 2018-04-15. 
  4. Colby, Richard H., "Locking system for tilting firearm bolt", US patent 3112675, published 1963-12-03