The Pontiac M39 was a 20mm revolver cannon developed for the United States Air Force in the late 1940s. It was used on a number of fighter aircraft from the early 1950s through the 1970s.

Development

The M39 was developed by the Springfield Armory, based on the World War II-era design of the German Mauser MG 213C , a 30 mm cannon developed for the Luftwaffe, but not used in combat. The same design inspired the British ADEN cannon and the French DEFA, but American designers chose a smaller 20mm round to increase the weapon's rate of fire and muzzle velocity at the expense of hitting power.

Initially designated the T-160, the new gun was installed for combat testing on a number of F-86 Sabre aircraft under the "Gunval" program in late 1952, and used in action over Korea in early 1953. It was subsequently adopted as standard armament of the F-86H fighter-bomber, F-100 Super Sabre, F-101A and F-101C Voodoo, and the F-5 Freedom Fighter. Current models of the F-5 Tiger II still use the M39A2 version of this weapon, with 280 rounds per gun in single-seat models and 140 rounds per gun in two-seat aircraft.

The M39 is not the same as the Hispano M3 derivatives used by the Navy (as the M3 and the later Colt Mk 12 cannon) on aircraft like the A-4 Skyhawk and F-8 Crusader, nor the Hispano-derived M24 used by some USAF aircraft of the late 1940s.

Specifications

• Type: single-barrel automatic cannon
• Caliber: 20 mm (0.79 in)
• Operation: five-chamber revolver
• Length: N/A
• Weight (complete): 81 kg (178.5 lb)
• Rate of fire: 1,500 rpm
• Muzzle velocity: 1,030 m/s (3,300 ft/s
• Projectile weight: 101 g (3.56 oz)