This upper offers a 1:8 RH military twist rate. The Faxon gunner barrel is made of chrome-moly 4150 steel. The barrel is threaded in 5/8x24. The upper is Mil-spec with M-4 feed ramps. We use a Anderson MFG M-16 bolt carrier for this 7.62. An optional Rubber City Armory Enhanced Black Nitride M-16 bolt carrier can be substituted for an additional fee. The front sight is a F-Marked with bayonet lug. The handguard is mil-spec. The flash hider is a A2 style. Comes with a Mil-Spec charging handle. We test fire these with American Ammo our 7.62's will fire Russian Ammo.