The Gatling gun is a rapid-firing multiple-barrel firearm invented in 1861 by Richard Jordan Gatling. It is an early machine gun and a forerunner of the modern electric motor-driven rotary cannon.
A machine gun (MG) is a fully automatic and rifled firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles are typically designed more for firing short bursts rather than continuous firepower and are not considered true machine guns. Submachine guns fire handgun cartridges rather than rifle cartridges, therefore they are not considered machine guns, while automatic firearms of 20 mm (0.79 in) caliber or more are classified as autocannons rather than machine guns.
The M61 Vulcan is a hydraulically, electrically, or pneumatically driven, six-barrel, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm × 102 mm rounds at an extremely high rate. The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft for over sixty years.
The MG 34 is a German recoil-operated air-cooled general-purpose machine gun, first tested in 1929, introduced in 1934, and issued to units in 1936. It introduced an entirely new concept in automatic firepower – the Einheitsmaschinengewehr – and is generally considered the world's first general-purpose machine gun (GPMG). Both the MG 34 and MG 42 were erroneously nicknamed "Spandau" by Allied troops, a carryover from the World War I nickname for the MG 08, which was produced at the Spandau Arsenal.
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.
An automatic firearm or fully automatic firearm is a self-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new ammunition round into the chamber, and then igniting the propellant and discharging the projectile by delivering a hammer or striker impact on the primer.
A mitrailleuse is a type of volley gun with barrels of rifle calibre that can fire either all rounds at once or in rapid succession. The earliest true mitrailleuse was invented in 1851 by Belgian Army captain Fafschamps, ten 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 revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, similar to those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to further speed the loading process. Unlike a rotary cannon, a revolver cannon only has a single barrel, so its spun weight is lower. Automatic revolver cannons have been produced by many different manufacturers.
The M134 Minigun is an American 7.62×51mm NATO six-barrel rotary machine gun with a high rate of fire. It features a Gatling-style rotating barrel assembly with an external power source, normally an electric motor. The "Mini" in the name is in comparison to larger-caliber designs that use a rotary barrel design, such as General Electric's earlier 20 mm M61 Vulcan, and "gun" for the use of rifle ammunition as opposed to autocannon shells.
The Stoner 63 is a 5.56×45mm NATO modular weapon system. Using a variety of modular components, it can be configured as an assault rifle, carbine, top-fed light machine gun, belt-fed squad automatic weapon, or as a vehicle mounted weapon. Also known as the M63, XM22, XM23, XM207 or the Mk 23 Mod 0 machine gun, it was designed by Eugene Stoner in the early 1960s. Cadillac Gage was the primary manufacturer of the Stoner 63 during its history. The Stoner 63 saw very limited combat use by United States forces during the Vietnam War. A few were also sold to law enforcement agencies.
The Hotchkiss gun can refer to different products of the Hotchkiss arms company starting in the late 19th century. It usually refers to the 1.65-inch (42 mm) light mountain gun; there were also a navy (47 mm) and a 3-inch (76 mm) Hotchkiss guns. The 42 mm gun was intended to be mounted on a light carriage or packed on two mules to accompany a troop of cavalry or an army travelling in rough country.
A rotary cannon, rotary autocannon, rotary gun or Gatling cannon, is any large-caliber multiple-barreled automatic firearm that uses a Gatling-type rotating barrel assembly to deliver a sustained saturational direct fire at much greater rates of fire than single-barreled autocannons of the same caliber. The loading, firing and ejection functions are performed simultaneously in different barrels as the whole assembly rotates, and the rotation also permits the barrels some time to cool. Rotary cannons, external or self-driven are used in aircraft over reciprocating bolt autocannons which are more prone to jamming in high g environments. The rotating barrels on nearly all modern Gatling-type guns are powered by an external force such as an electric motor, although internally powered gas-operated versions have also been developed.
An ammunition belt is a firearm device used to package and feed cartridges, typically for rapid-firing automatic weapons such as machine guns. Belt-fed systems minimize the proportional weight of the ammunition apparatus to the entire weapon system, and allow high rates of continuous fire without needing frequent magazine changes. The capacity of belts and associated belt containers is typically a function of weight and bulk, and their size is limited by caliber and the combined portability of the weapon and ammunition. Typical capacities for man-portable weapon systems range from 50 to 300 rounds of ammunition.
The Type 96 25 mm gun was an automatic cannon used by the Imperial Japanese Navy during World War II. A locally-built variant of the French Hotchkiss 25 mm anti-aircraft gun, it was designed as a dual-purpose weapon for use against armored vehicles and aircraft, but was primarily used as an anti-aircraft gun in fixed mounts with one to three guns.
The Gardner gun was an early type of mechanical machine gun. It had one, two or five barrels, was fed from a vertical magazine or hopper and was operated by a crank. When the crank was turned, a feed arm positioned a cartridge in the breech, the bolt closed and the weapon fired. Turning the crank further opened the breechblock and extracted the spent case.
The XM214 Microgun is an American prototype 5.56 mm rotary-barreled machine gun. It was designed and built by General Electric. The XM214 was a scaled-down smaller and lighter version of the M134 Minigun, firing M193 5.56×45mm ammunition.
A quick-firing or rapid-firing gun is an artillery piece, typically a gun or howitzer, that has several characteristics which taken together mean the weapon can fire at a fast rate. Quick-firing was introduced worldwide in the 1880s and 1890s and had a marked impact on war both on land and at sea.
A multiple-barrel firearm is any type of firearm with more than one gun barrel, usually to increase the rate of fire or hit probability and to reduce barrel erosion or overheating.
The Agar gun was an early rapid fire machine gun developed during the US Civil War. The weapon was nicknamed the Coffee Mill Gun, and was also called the Union Repeating Gun.
A repeating firearm or repeater is any firearm that is capable of being fired repeatedly before having to be manually reloaded with new ammunition into the firearm.
"The Machine Gun, History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons" by George M. Chinn, Lieutenant Colonel, USMC. Prepared for the Bureau of Ordnance, Department of the Navy, 1951
United States 
