M61 Vulcan
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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. Wikipedia
Designed: 1946
Range: About 9,842 ft
Barrels: 6-barrel (progressive RH parabolic twist, 9 grooves)
Caliber: 20 mm (0.787 in)
Cartridge: 20×102mm Vulcan
Feed system: Belt or linkless feed system
In service: 1959–present