Firearm action
In firearms terminology, an action is the system of operation used to load rounds and/or seal the breech. In many weapons a breechblock reciprocates in the receiver of the firearm.
The term is also used for the physical parts inside the weapon that carry out the system of operation.
Actions are generally divided on the basis of what provides the energy for its cycle, and how they lock the breech.
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Automatic actions
Recoil operation
- main article: Recoil operation
Recoil operation is a type of locked-breech firearm action used in semi-automatic and fully-automatic firearms. As the name implies, these actions use the force of recoil to provide the energy to cycle the action.
Weapons using recoil operation
- Short-recoil - Colt M1911, CZ75, Browning Hi-Power, HK USP, Glock, M2 Browning machine gun, MG42, Ceska Zbrojovka Vz 52, M82
- Long-recoil - Browning Automatic Shotgun, Femaru STOP Pistol, Mars Automatic Pistol
- Inertia - some Benelli shotguns
Blowback/Blowforward operation
- main article: Blowback
Blowback operation is a system in which semi-automatic and fully-automatic firearms operate through the energy created by combustion in the chamber and bore acting directly on the bolt face through the cartridge.
Weapons using blowback operation
- Simple blowback - MP 18, MP 40, Uzi submachine gun, Walther PPK
- Roller-delayed blowback - SIG 510, CETME, HK G3, HK MP5, HK P9
- Gas-delayed blowback - HK P7, Steyr GB, Volksturmgewehr
- Lever-delayed blowback - FAMAS, AA-52
- Toggle-delayed blowback - Schwarzlose MG M.07/12 and Pedersen rifle
- Chamber-ring delayed blowback - as in the Seecamp pistol
- Hesitation locked - Remington 51 pistol
- Blish Lock - early Thompson submachine guns
- Blowforward - Steyr Mannlicher M1894, SIG AK53, Hino-Komuro, Schwarzlose Pistol
Gas operation
- main articles: Gas-operated reloading, Direct impingement
Gas operation is a system of operation used to provide energy to semi-automatic and fully-automatic firearms. In gas-operation, a portion of high pressure gas from the cartridge being fired is used to extract the spent case and chamber a new cartridge.
Weapons using gas operation
- Short-stroke gas piston - FN FAL, AK-47, HK G36,
- Long-stroke gas piston - M1 Garand
- Direct impingement - M16, AG-42
Manual operations
Manual operation is a firearms term describing any type of firearm action that is loaded one shot at a time by the user rather than automatically. For example, break action is a form of manual operation using a simple hinge mechanism that is manually unlatched by the operator exposing the chamber(s) for reloading.
Bolt action
- main article: Bolt action
In Bolt action firearms, the opening and closing of the breech is operated manually by a bolt. Opening the breech ejects a cartridge while subsequently closing the breech chambers a new round. The three predominant bolt-action systems are the Mauser, Lee-Enfield, and Mosin-Nagant systems.
Lever action
- main article: Lever action
Lever action firearms uses a lever to eject and chamber cartridges. An example of firearms using lever action are the Winchester Repeating Rifle and Marlin Model 1894.
Pump action
- main article: Pump-action
In Pump action firearms, a grip called the fore end is manually operated by the user to eject and chamber a new round. Pump actions are predominantly found in shotguns. An example of firearms using the pump action are the Remington 870 and Winchester Model 1897
Break action
- main article: Break action
A Break action is a type of firearm where the barrel(s) are hinged and can be "broken open" to expose the breech. Multi-barrel break action firearms are usually subdivided into over-and-under or side-by-side configurations for two barrel configurations or "combination gun" when mixed rifle and shotgun barrels are used.
Falling Block
- main article: Falling Block
A Falling Block action is a type of single shot firearm where the opening and closing of the breech is activated by a lever. An example of a firearm using the Falling block action are the Martini-Henry and Ruger No. 1.
Other
Other methods of operation include Nordenfelt action, the Gardner gun action, the Rolling block action, the Screw breechblock action, the Rotating crank action, the Trapdoor action, the Snider breechblock and Lock breechblock action.
