A minigun is a multi-barreled machine gun with a high rate of fire, employing Gatling style rotating barrels. The general opinion that the purpose of multibarrel design is to prevent overheating is only partially true. Apparently, six barrels allow to achieve breathtaking firing rate through the parallel processes of firing/extraction/loading taking place in all barrels simultaneously (for example, as one barrel fires, two others are in different stages of shell extraction and another three are being loaded, though the actual process scheme may be different from what is described here). The minigun is composed of six closed-bolt rifle barrels arranged in a circular housing. The gun is not automatic, as in gas-operated or recoil-operated machine guns. It must be powered externally by electric, pneumatic, or hydraulic means.
When the US entered the Vietnam War during early 1960s, they found they needed to arm their helicopters to provide additional firepower against enemy infantry. Those applications also required a high rate of fire delivered in short bursts, so General Electric designers simply scaled down the 20 mm M61 Vulcan for 7.62 x 51 mm NATO ammunition. The resulting weapon, known as the M134 Minigun, could fire up to 4000 rounds per minute, and was soon adapted to the various helicopter mounts. It was mounted on CH-47 Chinook turrets, in wing pods on AH-1 Cobra attack helicopters, on door, pylon and pod mounts on UH-1 "Huey" Iroquois transport helicopters and on many other helicopters and aircraft.
Several larger aircraft were outfitted with miniguns, specifically for close air support, including famous "Gunship" airplanes like the Douglas AC-47 ("Spooky" aka "Puff the Magic Dragon", converted Douglas DC-3's); AC-119 Gunships[1] ("Shadow" and "Stinger", converted Fairchild "Flying Boxcars"); and the original AC-130 "Spectre" Gunship (converted C-130 Hercules cargo planes).
Pop Culture
As an armament of the Vietnam War, the minigun received some screen-time in war-themed movies. But it was not until the science-fiction thriller Predator (1987), that the minigun dazzled moviegoers. In Predator, an American special-forces soldier wears a portable minigun and operates it in a tactically impossible manner, as a hand-held machine-gun. The famous film-sequence was captured in typical Hollywood fashion: with specially constructed props and with little regard for the minigun's real-life tactical-employment. First, the actor's (Jesse Ventura) weapon, though authentic, fired specially-loaded reduced-charged blanks, as full-charge ammo would produce too much recoil. Second, the external electrical-power to spin the gun-barrels was supplied through a cable hidden underneath the actor's uniform, giving the false impression of a self-powered unit. And finally, the minigun's longest on-screen firing-time exceeded 20 (continuous) seconds. A real minigun (at 4000rpm) would consume 1,300 rounds of 7.62 mm ammo, weighing over 100lbs (55kg.) Although not an unrealistic load for a muscle-bound soldier, it is doubtful that such a burdensome weapon-system would be carried behind enemy lines, on foot.
Nevertheless, the movie's minigun spectacle inspired many copycats. Today, the minigun is a staple of action videogames such as the Wolfenstein and Doom franchises (where it is called a "chain gun") and the Hitman series.
The XM-214 minigun had the potential to be the man-portable weapon used in pop culture. This was a scaled-down version of the M-134, firing 5.56mm NATO ammunition. Firing the same ammunition as the M-16 rifle, XM-214 was offered by General Electric as a squad support machine gun. The gun system was supplied with 1000 rounds in a backpack, known as the GE SixPack. Weighing 85 pounds with a tripod, the weapon system could be carried and fired by a team of two soldiers. The gun had a user-adjustable firing rate between 400 rpm and 4000 rpm. If the tripod was exchanged for extra ammunition, and the rate of fire held to a more reasonable 1000-1200 rpm, a disciplined gunner could fire the weapon "Hollywood style" (standing up) continuously for 1 minute. Unfortunately, the XM-214 never made it past the prototype stage.
External link
Sources for Revision: http://www.stormpages.com/monkeypool/minigun.html http://www.fas.org/man/dod-101/sys/ac/equip/m134.htm http://world.guns.ru/machine/minigun-e.htm
The information about the XM-214 gun was drawn from a book called the Arsenal of Democracy. Unfortunately my copy is so battered I no longer have the page with copyright and publisher information.