The M42 40 mm Self-Propelled Anti-Aircraft Gun, or "Duster," is an American armored light air-defense gun built for the United States Army from 1952 until December 1960, in service until 1988. Production of this vehicle was performed by the tank division of the General Motors Corporation. It used components from the M41 light tank and was constructed of all-welded steel.
A total of 3,700 M42s were built. The vehicle has a crew of six and weighs 22,500 kg (49,500 lb) fully loaded. Maximum speed is 45 mph (72 km/h) with a range of 100 miles (160 km). Armament consists of fully automatic twin 40 mm M2A1 Bofors, with a rate of fire of 2×120 rounds per minute (rpm) enabling nearly 85 seconds of fire time before running out of ammo, and either a .30 caliber Browning M1919A4 or 7.62mm M60 machine gun. The 500 hp, six-cylinder, Continental (or Lycoming Engines), air-cooled, gasoline engine is located in the rear of the vehicle. It was driven by a cross-drive, two-speed Allison transmission.
Although the M42 Duster was initially designed for an anti-aircraft role, it proved to be effective against unarmored ground forces in the Vietnam war.
