9.2″ Upper with GPX-9 Rail System
…PREMIUM 9.2″ Pistol Upper w/ M4 Nickel Boron Barrel Extension 9.2″ Siphon AGP Barrel 4150 CrMoVa (5.56 NATO Chamber) Nitride Treated Barrel (inside & out) CARBINE Gas System (SIPHON AGP) 1:7 Twist Rate 1/2×28 Thread Pitch Nickel Boron M4 Barrel Extension with Extended Feed Ramps Nitride M16 Bolt Carrier Group w/Logo (properly staked w/Grade 8 hardware) Nitride Carbine Gas Tube (Nitride Treated) Nitride Micro Gas Block .750 (Nitride Treated) GPX-9…