The Colt-Browning Mk 12 was a 20 mm cannon widely used by the US 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 Two. It used a lighter projectile with a bigger charge for better muzzle velocity and faster rate of fire at the cost of hitting power. It entered US Navy and USMC 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 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, F-3 Demon, A-4 Skyhawk, F-8 Crusader, and A-7 Corsair II.

The Mk 12 is not the same as the Pontiac M39 cannon used on the F-100 and F-101 of the USAF, despite the similar caliber.

Specifications

• Type: single-barrel automatic cannon
• Caliber: 20 mm (0.79 in)
• Operation: gas
• Length: N/A
• Weight (complete): 46 kg (101.4 lb)
• Rate of fire: 1,000 rpm
• Muzzle velocity: 1,010 m/s (3,300 ft/s
• Projectile weight: 110 g (3.88 oz)