Phase 5’s most popular AR type pistol barrel is a 1:7 twist, air gauged, button rifled barrel chambered for 5.56 NATO ammunition. This barrel is combined with an M4 barrel extension with M4 feed ramps. It has been heat treated and stress relieved for excellent durability. Made of a 41v50 chromoly alloy steel, this barrel has excellent wear resistance, which makes it perfect for any build. Coating is a complete satin black manganese phosphate finish.