Premium barrel configuration for hard use with classic hard chrome bore and chamber. The Brownells Premium Lightweight Carbine Barrels come in a variety of popular lengths, ready to suite any new carbine build. Ballistic Advantage is manufacturing these to Brownell's specifications and quality standards, ensuring you get the best barrel possible. Barrel exteriors are coated with the standard phosphate finish, which provides an excellent matte finish, and retains oil extremely well. The most important aspect of the barrel, the bore and chamber, are hard chromed, to prevent corrosion, ease cleaning and prevent long term wear. The button rifled barrels, profiled from 4150 Chrome M Mfg: Brownells