This 5.56 chambered 16 inch Performance Series Barrel is machined from 4150 Chrome Moly Vanadium steel with a QPQ Corrosion Resistant Finish. Ballistic Advantage's Performance Series Barrels feature a Nickel Boron Coated Extended M4 Feed Ramp Extension. Hanson Series Barrels feature Ballistic Advantage's proprietary BA Hanson profile and include a pinned lo-pro gas block. Hanson barrels are not designed to work with aftermarket piston kits.