Gatling gun
Similar systems are available ranging from 5.56 mm to 30 mm (there was even a 37 mm Gatling on the prototype T249 'Vigilante' AA platform); During the Vietnam War, the 7.62 mm calibre M134 Minigun was created as a helicopter weapon. The M61 Vulcan 20 mm cannon is the most commonly-used member of a family of weapons designed by General Electric and currently manufactured by General Dynamics. In contrast, a five-barreled Gatling gun-style weapon firing 2000 rounds fires 400 per barrel, an acceptable rate of fire. One of the main reasons for the resurgence of the Gatling gun-style design is the weapon's tolerance for continuous high rates of fire. After Gatling guns were replaced by lighter, cheaper blowback-style weapons, the approach of using multiple rotating barrels fell into disuse for many decades. However, Gatling gun-style weapons made a return in the 1940-50s, when weapons with very high rate of fire were needed in military aircraft such as the Lockheed AC-130 gunship...