The m1 abrams is a modern, third-generation american main battle tank. The first prototypes of the vehicle were built in the 1970s, and serial production began in 1979 and continues to this day. To date (2018), approximately 10,500 tanks of this type have been produced. The m1 abrams is powered by a 1,500 hp avco lycoming agt-1500c turboshaft (turbine) engine. The vehicle's armament includes the 105 mm m68a1 tank gun in the m1 version, and the 120 mm m256 tank gun in the m1a1 and later versions. Additional armament includes one 12. 7 mm machine gun and two 7. 62 mm m240 machine guns