In December 1950 the Army awarded a $100 million contract to the American Locomotive Company for the production of 500 tanks. It entered production in 1951. Its main gun was the M36 90 mm gun with an M12 optical rangefinder fitted. The secondary armament consisted of two .30 cal Browning machine guns, one in the bow and one coaxial with the 90mm main gun in the turret, and a .50 caliber Browning M2 on a pintle mount on the turret roof. The M47 was the last American-designed tank to include a bow machine gun. The T42 turret had a larger turret ring than the M26/M46 turret, and featured a needle-nose design, which improved armor protection of the turret front, an elongated turret bustle and storage bin which protruded halfway across the engine deck, and sloped sides to further improve ballistic protection; this gave the turret a decidedly lozenge-shaped profile. It also featured the M12 stereoscopic rangefinder, which was designed to improve first-round hit probability but proved difficult to use; the rangefinder protruded from both sides of the upper turret front, which would be a feature of American tanks until the advent of the M1 Abrams in 1980.