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 (0.787 in × 4.016 in) rounds at an extremely high rate (typically 6,000 rounds per minute). The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft for over sixty years.
The M61 was originally produced by General Electric. After several mergers and acquisitions, it is produced by General Dynamics as of 2000.<sup> </sup>It is also manufactured under license in Japan by Sumitomo Heavy Industries for Japan's Self-Defense Force and by SNT Dynamics in South Korea