A light machine gun (LMG) is a machine gun designed to be employed by an individual soldier, with or without an assistant, as an infantry support weapon. Light machine guns are often used as squad automatic weapons.
A rotary cannon, rotary autocannon, or Gatling-type cannon is a rapid-firing weapon that utilizes multiple barrels in a rotating cluster to provide a sustained rate of fire greater than single-barreled machine guns or automatic cannon of equivalent caliber. The loading, firing, and unloading functions are performed simultaneously in different barrels as they rotate, and the rotation also permits the barrels some time to cool. The rotating barrel cluster on most Gatling-type guns is powered by an external force such as an electric motor, although gas-operated versions have also been developed.
A general-purpose machine gun (GPMG) is an air-cooled, fully automatic weapon that can be adapted to light machine gun and medium machine gun roles. A GPMG weapon will typically feature a quick-change barrel, configuration for mounting on bipods, tripods, and vehicles as infantry support weapons, and calibered to fire full-powered rifle cartridges such as the 7.62×51mm NATO, 7.62×54mmR, 7.5×54mm French, 7.5×55mm Swiss, and 7.92×57mm Mauser.
The Colt–Browning M1895, nicknamed "potato digger" because of its unusual operating mechanism, is an air-cooled, belt-fed, gas-operated machine gun that fires from a closed bolt with a cyclic rate of 450 rounds per minute. Based on a John Browning and Matthew S. Browning design dating to 1889, it was the first successful gas-operated machine gun to enter service.
The Maschinengewehr 30, or MG 30 was a German-designed machine gun that saw some service with various armed forces in the 1930s. It was also modified to become the standard German aircraft gun as the MG 15 and MG 17. It is most notable as the design pattern that led to the MG 34 and MG 42, and thus is one of the major ancestors of many of the weapons in service which would later find widespread use into the 21st century.
A mitrailleuse is a type of volley gun with multiple barrels of rifle calibre that can fire either multiple rounds at once or several rounds in rapid succession. The earliest true mitrailleuse was invented in 1851 by Belgian Army Captain Fafschamps, 10 years before the advent of the Gatling gun. It was followed by the Belgian Montigny mitrailleuse in 1863. Then the French 25 barrel "Canon à Balles", better known as the Reffye mitrailleuse, was adopted in great secrecy in 1866. It became the first rapid-firing weapon deployed as standard equipment by any army in a major conflict when it was used during the Franco-Prussian War of 1870–71. A steel block containing twenty-five 13 mm centre-fire cartridges was locked against the breech before firing. With the rotation of a crank, the 25 rounds were discharged in rapid succession. The sustainable firing rate of the Reffye mitrailleuse was 100 rounds per minute. The maximum effective range of the Reffye mitrailleuse was about 2000 yards; a distance which placed their batteries beyond the reach of Prussian Dreyse needle rifle fire. Reffye mitrailleuses were deployed in six gun batteries and were manned by artillery personnel. They were not infantry support weapons but rather a form of special artillery.
The M45 Quadmount was a weapon mounting consisting of four of the "HB", or "heavy barrel" .50 caliber M2 Browning machine guns mounted in pairs on each side of an open, electrically powered turret. It was developed by the W. L. Maxson Corporation to replace the earlier M33 twin mount. Although designed as an anti-aircraft weapon, it was also used against ground targets. Introduced in 1943 during World War II, it remained in US service as late as the Vietnam War.
The Vickers .50 machine gun, also known as the 'Vickers .50' was basically similar to the .303 inches (7.70 mm) Vickers machine gun but scaled up to use a larger-calibre 0.5-inch (12.7 mm) round. It saw some use in tanks and other fighting vehicles, but was much more commonly used as a close-in anti-aircraft weapon on Royal Navy and allied ships, typically in a four-gun mounting. The Vickers fired UK .50 Vickers (12.7×81mm) 50-calibre ammunition, not the better known US (12.7×99mm).