Franklin Armory XO-26 11.5 inch 5.56 NATO Carbine Length Barrel Black 00-52500-BLK. 5 inch Pistol Barrel. 5.56 NATO. 1x7 Twist for 5.56 NATO. 4140 Steel. Salt Bath Nitride Chamber Bore and Finish. Carbine Length Gas System. A4 Barrel Extension 8620...