The M4A1 is a direct descendant of the M-16 rifle and is the standard battle rifle of U.S. forces. The rifle is capable of full automatic fire and chambered for 5.56 mm bullets.
The MK11 rifle is also based on the design of the M-16, this rifle features a telescopic sight and a detachable silencer.
The MK14 sniper rifle is basically an M-14 rifle modified for sniper use. The rifle is chambered for 7.62 mm and capable of full automatic fire.
The M82A1 is a 50 caliber semiautomatic sniper rifle manufactured by Barrett Firearms. This rifle fires the same 50 caliber bullets usually used in heavy machine guns.