This is the original A2 government profile 20″ barrel – perfect as a replacement barrel, or for that service rifle build you’ve been planning. Barrel material is 4150 Chrome Moly Vanadium11595E Steel, and it is Chrome Lined in both Bore and Chamber for long wear and ease of cleaning. Button rifling is 1 turn in 7 inches – right hand twist for optimum accuracy with a wide range of .223 / 5.56mm ammunition. A Black Manganese Phosphate finished is applied for protection against rust and corrosion. This barrel is machine turned under the handguards to offer the lightest weight possible. It includes the Barrel Extension (with M4 Feed Ramps), Barrel Nut ,Triangular Handguard Cap, standard A2 Front Sight Base with Sling Swivel, and Bayonet Lug. The muzzle is threaded 1/2″ x 28 T.P.I. to accept a variety of flash hiders or muzzle brakes. Includes a triangular Front Handguard Cap.