A minigun is a multi-barreled machine gun with a high rate of fire, employing Gatling style rotating barrels to prevent overheating. 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 20mm M61 Vulcan for 7.62x51mm 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).
The first movie to feature the impossibility of a hand-held minigun was Predator. The footage and gun were real, but reduced-power blank rounds were used, as an actual minigun produces recoil beyond human limits. The power to spin the weapon was supplied through a cord hidden underneath the actor's clothing. The concept caught on, however, and the minigun has figured prominently in video games and other movies ever since.
External link
Sources for Revision:
http://www.stormpages.com/monkeypool/minigun.html
http://www.fas.org/man/dod-101/sys/ac/equip/m134.htm
