In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.
The MG 42 is a German recoil-operated air-cooled general-purpose machine gun used extensively by the Wehrmacht and the Waffen-SS during the second half of World War II. Entering production in 1942, it was intended to supplement and replace the earlier MG 34, which was more expensive and took much longer to produce, but both weapons were produced until the end of World War II.
Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.
A breechblock is the part of the firearm action that closes the breech of a breech loading weapon before or at the moment of firing. It seals the breech and contains the pressure generated by the ignited propellant. Retracting the breechblock allows the chamber to be loaded with a cartridge.
Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent case and insert a new cartridge into the chamber. Energy from the gas is harnessed through either a port in the barrel or a trap at the muzzle. This high-pressure gas impinges on a surface such as a piston head to provide motion for unlocking of the action, extraction of the spent case, ejection, cocking of the hammer or striker, chambering of a fresh cartridge, and locking of the action.
Rotating bolt is a method of locking the breech of a firearm closed for firing. Johann Nicolaus von Dreyse developed the first rotating bolt firearm, the "Dreyse needle gun", in 1836. The Dreyse locked using the bolt handle rather than lugs on the bolt head like the Mauser M 98 or M16. The first rotating bolt rifle with two lugs on the bolt head was the Lebel Model 1886 rifle. The concept has been implemented on most firearms chambered for high powered cartridges since the 20th century.
In firearms operating systems, the term roller locked refers to locking the bolt with rollers. Notable examples of firearms using this method are the MG 42 general-purpose machine gun, and the CZ 52 semi-automatic pistol. It was also applied in the experimental Gerät 03 semi-automatic rifle and Gerät 06 and EM-1 experimental assault rifles. The MG 42's lineage continued past World War II, forming the basis for the nearly identical MG1, chambered in 7.62×51mm NATO, which subsequently evolved into the MG1A3, and later the Bundeswehr's MG 3, Italian MG 42/59 and Austrian MG 74. It also spawned the Yugoslav unlicensed nearly identical Zastava M53.
The Heckler & Koch HK33 is a 5.56mm assault rifle developed in the 1960s by West German armament manufacturer Heckler & Koch GmbH (H&K), primarily for export.
A bolt is the part of a repeating, breechloading firearm that blocks the rear opening (breech) of the barrel chamber while the propellant burns, and moves back and forward to facilitate loading/unloading of cartridges from the magazine. The firing pin and extractor are often integral parts of the bolt. The terms "breechblock" and "bolt" are often used interchangeably or without a clear distinction, though usually, a bolt is a type of breechblock that has a nominally circular cross-section.
The Heckler & KochG41 is a German 5.56×45mm NATO assault rifle introduced in 1981 and produced in limited quantities by Heckler & Koch. It was designed to replace the 7.62×51mm NATO chambered Heckler & Koch G3 and the G3 based .223 Remington/5.56×45mm and later 5.56×45mm NATO chambered Heckler & Koch HK33 service rifles providing a more modern weapon compatible with then recently introduced NATO standards. It can use both the then new STANAG 4172 compliant 5.56×45mm NATO SS109, SS110, and SS111 ammunition and older .223 Remington/5.56×45mm M193 ammunition and was the last Heckler & Koch service rifle designed around the roller-delayed blowback mechanism.
The HK21 is a German 7.62 mm general-purpose machine gun, developed in 1961 by small arms manufacturer Heckler & Koch and based on the G3 battle rifle. The weapon is in use with the armed forces of several Asian, African and Latin American countries. It was also license-manufactured by Fábrica de Braço de Prata in Portugal as the m/968 and in Mexico by SEDENA as the MG21. In the German military (Bundeswehr) and the federal police (Bundespolizei) it is designated "G8".
The SIG MG 710-3 is a Swiss 7.62 mm general-purpose machine gun (GPMG) designed and manufactured by SIG - Schweizerische Industrie Gesellschaft. The weapon was developed as a commercial venture primarily for export, since the Swiss Army had already adopted the 7.5 mm MG 51 GPMG, produced by the federal arms factory W+F.
The Ameli is a 5.56mm light machine gun designed for the Spanish Army by the nationally owned and operated Centro de Estudios Técnicos de Materiales Especiales (CETME) small arms research institute.
The Volkssturmgewehr is the name of several rifle designs developed by Nazi Germany during the last months of World War II. They share the common characteristic of being greatly simplified as an attempt to cope with severe lack of resources and industrial capacity in Germany during the final period of the war. The Volkspistole was a partner program, almost identical, but for pistols instead.
The StG 45(M) (abbreviation of Sturmgewehr 45, "Assault Rifle 45") sometimes referred to as the MP 45(M), was a prototype assault rifle developed by Mauser for the Wehrmacht at the end of World War II, using an innovative roller-delayed blowback operating system. It fired the 7.92×33mm Kurz (or "Pistolenpatrone 7.9mm") intermediate cartridge at a cyclic rate of around 450 rounds per minute.
In firearms terminology, fluting refers to the removal of material from a cylindrical surface, usually creating grooves. This is most often the barrel of a rifle, though it may also refer to the cylinder of a revolver or the bolt of a bolt action rifle. In contrast to rifle barrels and revolver cylinders, rifle bolts are normally helically fluted, though helical fluting is sometimes also applied to rifle barrels.
Recoil operation is an operating mechanism used to implement locked breech, autoloading firearms. Recoil operated firearms use the energy of recoil to cycle the action, as opposed to gas operation or blowback operation using the pressure of the propellant gas.
The Garanin machine guns were a series of general-purpose machine gun prototypes developed by Soviet designer Georgy Semenovich Garanin at OKB-575 in Kovrov. These guns were developed in the context of a contest, started in December 1955, for replacing the company-level RP-46 light machine gun and the battalion-level "heavy" machine gun SGM with a single new machine gun that could fulfill both roles using different mounts.
Grossfuss Sturmgewehr was a prototype assault rifle designed during World War II by Kurt Horn at the Grossfuss company better known for their contribution to the German arsenal made with the MG 42.
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.
