The JP Enterprise JP-15 upper receiver assembly is built on a forged upper with a 16" Supermatch barrel. The lightweight barrel is made of 416 stainless steel, button rifled and cryogenically treated for outstanding accuracy. The 223 Wylde chamber is designed to be best of both the SAAMI commercial specification and the NATO chambering, allowing the widest variety of ammunition to be used, while retaining accuracy. The 1 in 8" twist rifling produces good results with bullet weights from 40 to 77 grains. The 16" barrel threaded 1/2"-28 with a JP Tactical Compensator. The Low Mass Bolt carrier is constructed of stainless steel with a QPQ finish. The QPQ finish is a five step treatment of polishing and hardening of the surface resulting in a very hard surface with a high level of lubricity. The bolt is constructed of SAE 9310 steel and exceeds the standard mil-spec in strength and service life. The low mass bolt carrier group and adjustable gas block work together t...