This is a premium grade 16" AR-15 Heavy Barrel from a renowned U.S. contractor/barrel manufacturer. These premium barrels are renowned for their deep, crisp, and consistent rifling and extreme accuracy. These parkerized barrels start with 4140 Gun Barrel quality steel and are then heat-treated and stress relieved to a hardness of Rockwell C 28-32. These barrels are manufactured on modern CNC equipment to machine the barrel completely. They drill, ream, rifle, turn, chamber ream, pin the Barrel Extension, drill the gas hole, and mill the flutes, all on late model CNC Equipment. The Barrels are manufactured under the ISO 9002 Quality System and go through a Final Inspection before shipping.