Colt Mk 12 cannon

Colt Mk 12
250px A pair of Mk 12 cannons in the forward fuselage of a Chance-Vought F-8 Crusader.
Type	Autocannon
Place of origin	United States
Service history
In service	1950s–1960s
Used by	United States Navy
Wars	Vietnam War
Specifications
Weight	46 kg (101 lb)
Caliber	20 (0.79 in) mm × 110 mm (USN)
Action	Gas-operated reloading
Rate of fire	1,000 rpm
Muzzle velocity	1,010 m/s (3,300 ft/s)

The Colt-Browning Mk 12 was a 20 mm cannon widely used by the United States Navy after World War II.

Development

The Mk 12 was an advanced derivative of the wartime Hispano HS 404 that had been used on a variety of American and British fighter aircraft during World War II. It used a lighter projectile with a bigger charge for better muzzle velocity and higher rate of fire at the cost of hitting power. It entered U.S. Navy and U.S. Marine Corps service in the mid-1950s, replacing the Navy's earlier M3 cannon.

In service, the Mk 12 proved less than satisfactory. Although its muzzle velocity and rate of fire were acceptable, it was inaccurate and frequently unreliable. Pilots of the F-8 Crusader over North Vietnam, in particular, appreciated the presence of the cannon, but jams and stoppages were common, especially following hard dogfighting maneuvers.

Nevertheless, the Mk 12 was standard cannon armament on gun-armed Navy and Marine Corps fighters from the early 1950s to the early 1960s, including the F4D Skyray, F3H Demon, A-4 Skyhawk, F-8 Crusader and Navy versions of the A-7 Corsair II. The Air Force version of the Corsair II, the A-7D, had a six-barreled M61A1 rotary 20mm cannon.

The Mk 12 is not the same as the Pontiac M39 cannon used on the F-100 Super Sabre, F-101 Voodoo, F-5A Freedom Fighter and F-5E Tiger II fighters of the U.S. Air Force, despite the similar caliber.