The not-so-mini, M134 Mini Gun
Named in honor of the Roman god of fire, the “Vulcan” minigun could not be more aptly named. More formally known as the M61, or M134 Minigun, this six-barreled monster of a weapon has delivered hell on Earth to any who find themselves unlucky enough to be in its sights. The M61 is a 7.62mm NATO-round six-barrel rotary machine gun with a rapid-fire rate of 2,000 to 6,000 rounds per minute. It has a spinning barrel assembly in the Gatling style with an external power source, typically an electric motor.
"Mini" refers to smaller-caliber models with rotary barrels, like General Electric's earlier 20 mm M61 Vulcan. In contrast, "gun" refers to using rifle ammunition rather than autocannon rounds. The name "minigun" originally referred to a particular sort of weapon that General Electric built. Still, it has since spread to mean any externally driven rotary gun with a rifle caliber. Regardless of the source of power or caliber, the word is occasionally used informally to describe weapons with comparable rates of fire and configurations.
But where did it all begin?
Richard Jordan Gatling created a hand-cranked mechanical device in the 1860s that served as the forerunner to the contemporary minigun. Later, he switched a rifle-caliber Gatling gun's hand-cranked mechanism for an electric motor, which was still a relatively recent innovation. The new electric-powered Gatling gun had a theoretical rate of fire of 3,000 rounds per minute even after Gatling slowed the mechanism, which is nearly three times the pace of a typical modern, single-barreled machine gun. On July 25, 1893, Gatling's electric-powered invention was granted U.S. Patent #502,185. Despite his advances, the Gatling gun was abandoned in favor of less expensive, lighter, recoil-operated machine guns; Gatling even briefly declared bankruptcy.
Several German businesses were developing similar externally propelled guns for use in aircraft during World War I. The Fokker-Leimberger, an externally powered 12-barrel rotary gun that fired the 7.9257mm Mauser round, is likely the most well-known of these today. It was advertised as having a firing rate of nearly 7,000 rpm but frequently experienced cartridge-case ruptures due to its "nutcracker" rotating split-breech design, which differs significantly from traditional rotary gun designs.
None of these German weapons entered production during the conflict. However, a Siemens prototype competed with them and was tested on the Western Front, winning an aerial battle (perhaps employing a different action). During the 1950s, the British tried out this style of the split breach, but they also failed. But, where they all failed, the United States would succeed in the 1960s with the “Vulcan” cannon.
And so, the United States Armed Forces started looking into contemporary versions of the revolving barrel, electric-powered Gatling-style weapons in the 1960s for use in the Vietnam War. They succeeded, with the weapon originally designed for use in helicopters but has since been adapted for various other aircraft and ground-based infantry use. The U.S. military has used the M134 extensively in several conflicts, including in Vietnam, Iraq, and Afghanistan. Other countries and non-governmental organizations have also used the weapon. The weapon is still in use today in various forms and platforms.
Several U.S. military branches employ the Minigun. The American Army has version M134, and the American Air Force and the American Navy have GAU-2/A and GAU-17/A, respectively. The weapon is typically mounted on vehicles, aircraft, or watercraft and is operated by a single gunner. It has been used by various military forces worldwide and is still in service today.