This report is directed to personnel charged with the use, care, and maintenance of the Caliber 7.62mm t44E5 M15 Rifle. The subject rifle is a heavy barrel version of the Caliber 7.62mm T44E4 M14 Rifle, designed to permit sustained full automatic fire. The caliber 7.62mm, T44E5 M15 rifle is a heavy barreled, aircooled, gas-operated, magazine-fed, shoulder weapon, designed for selective semiautomatic fire. In principle of operation, it is similar to the M1 rifle. The T44E5 is chambered for the NATO caliber 7.62mm cartridge, and a 20-round box magazine has been added.