M61A1 Vulcan

M61 Vulcan
An unmounted M61 Vulcan.
Type	Rotary cannon
Place of origin	United States
Service history
In service	1959–present
Used by	United States, some NATO members, South Korea, Saudi Arabia, and others
Wars	Vietnam War Gulf War War in Afghanistan Iraq War
Production history
Designed	1946
Manufacturer	General Electric
Variants	See below
Specifications
Weight	M61A1: 248 pounds (112 kg) without feed system M61A2: 202 pounds (92 kg) without feed system
Length	71.93 in (1.827 m)
Cartridge	20×102 mm
Caliber	20 mm (0.787 in)
Barrels	6-barrel (progressive RH parabolic twist, 9 grooves)
Action	Hydraulically operated, electrically fired, rotary cannon
Rate of fire	M61A1: 6,000 rounds per minute M61A2: 6,600 rounds per minute
Muzzle velocity	3,450 feet per second (1,050 m/s) with PGU-28/B round
Feed system	Belt or linkless feed system

The M61 Vulcan is a hydraulically or pneumatically driven, six-barrel, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm 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 fifty years.

The M61 was originally produced by General Electric. After several mergers and acquisitions, it is currently produced by General Dynamics.

At the end of World War II, the United States Army began to consider new directions for future military aircraft guns. The higher speeds of jet-powered fighter aircraft meant that achieving an effective number of hits would be extremely difficult without a much higher volume of fire. While captured German designs (principally the Mauser MG 213C) showed the potential of the single-barrel revolver cannon, the practical rate of fire of such a design was still limited by ammunition feed and barrel wear concerns. The Army wanted something better, combining extremely high rate of fire with exceptional reliability. In 1947, the Air Force became a separate branch of the military. The new Air Force made a request for a new aircraft gun. A lesson of World War II air combat was that German, Italian and Japanese fighters could attack American aircraft from long range with their cannon main armament. American fighters with .50 cal main armament, such as the P-51 and P-47, had to be close to the enemy in order to hit and damage enemy aircraft. The 20mm Hispano cannon carried by the P-38 and P-61, while formidable against propeller driven planes, had a relatively low rate of fire in the age of jets, while other cannons were notoriously unreliable.