Ballistic Advantage Hanson Midlength, 1:7 Twist Barrel, 556NATO, 16, Mid Length Gas System, Fits AR-15, Phosphate Finish, Black, Includes Low Pro Gas Block BABL556H13F This 5.56 NATO chambered 16 inch Cold Hammer Forged barrel is machined from CrMoV steel with a manganese phosphate finish and chrome lined bore. Their limited run of Cold Hammer Forged barrels feature an M4 Feed Ramp Extension and are HP and MPI tested.