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In firearms terminology, an action is the physical mechanism that manipulates cartridges and/or seals the breech. The term is also used to describe the method in which cartridges are loaded, locked, and extracted from the mechanism. Actions are generally categorized by the type of mechanism used. A firearm action is technically not present on muzzleloaders as all loading is done by hand. The mechanism that fires a muzzle-loader is called the lock.
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Manual operation
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.
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 acting directly on the breechblock and lowering it to expose the breech. An example of a firearm using the falling block action are the Martini-Henry and Ruger No. 1. A minor variation is the rolling block where the breechblock is pivoted out of the way.
Revolver
A revolver houses cartridges in a rotary cylinder and advances them in-line with the bore prior to each shot. Revolvers are most often handguns however examples of rifles and shotguns have been made. The cylinder is most often rotated by manipulation of the trigger and/or hammer although some are semi-automatic using recoil to rotate the cylinder and cock the hammer.
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
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
In pump action or slide 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
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.
Automatic actions
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.
Examples of 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
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.
Blow-Forward operation is where the firearm has a moving barrel that is forced forward against a spring by the friction of the projectile as means of reloading a fresh round.
Examples of blowback operation
- Simple blowback: MP 40, Uzi submachine gun, Walther PPK
- Roller-delayed blowback: SIG 510, HK MP5, HK P9
- Gas-delayed blowback: Volkssturmgewehr 1-5, HK P7, Steyr GB
- Lever-delayed blowback: FAMAS, AA-52
- Toggle-delayed blowback: Schwarzlose MG M.07/12 and Pedersen rifle
- Blow-forward: Steyr Mannlicher M1894, Schwarzlose Model 1908
- Blish Lock: early Thompson submachine guns
- Hesitation locked: Remington 51 pistol
- Chamber-ring delayed blowback: Seecamp pistol
Gas operation
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. There are three basic types: long stroke gas piston (where the gas piston goes the same distance as the operating stroke of the action parts, and is often attached to the action parts), short stroke gas piston (where the gas piston goes less than distance as the operating stroke of the action parts), and direct impingement (AKA "direct gas", "gas impingement", where there is no piston, and the gas acts directly on the action parts). A fourth type, now considered obsolete and ineffective, are those systems based on the Bang rifle that utilize a muzzle cap to capture gas after the bullet has left the barrel. While this system is successful in boosting the operating power of recoil operated guns, it is insufficient and too susceptible to fouling for use as the primary operating system.
Examples of gas operation
- Short-stroke gas piston: FN FAL, HK G36
- Long-stroke gas piston: M1 Garand, AK-47
- Direct impingement: M16, AG-42
- Gas trap: Gewehr 41, Bang M1922 rifle[1]
Other
Other methods of operation include the Gardner gun, screw breechblock, rotating crank, the trapdoor, and Snider breechblock actions.
See also
References
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