300 BLK with pistol gas system for optimum reliability with super or subsonic ammo. Faxon Firearms barrels are the pinnacle of value. Manufactured 100% in-house from cradle-to-grave, these barrels are fully stress relieved, air-gauge tested, and 11 degree target crowned to ensure superior accuracy. Quality is imbued into our barrels from the start. We start with the best materials, either certified 4150 Mil-Spec steel or 416-R Stainless. From there, each barrel goes through a battery of tests at each operation until finished in Nitride and final inspected. All barrels are individually checked for headspace by precision custom hardened gauges. Barrel Material: 4150 Barrel Type: Button Rifled Barrel Caliber: 300BLK AAC Barrel Twist: 1:8RH Barrel Length: 10.5 Barrel Profile: Medium Barrel Gas System: Pistol Inside Finish: QPQ Nitride Outside Finish: QPQ Nitride Muzzle Thread: 5/8"-24 Gas Block Diameter: .750" Gas Hole Diameter: .075" Gas Block Journal Length: 1.9" Barrel Extension: M4 Weight: 1.15 lbs Magnetic Particle Inspected! 11-degree Target Crown