Faxon starts with 4150 Mil-Spec steel 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. Features button rifling; Big Gunner profile; carbine barrel gas system; Salt Wash Nitride inside and outside finish; M18x1.5 thread, tapered shoulder and 11 degree target crowned. 1.9" gas block journal. Product Specifications Category: Rifle Barrels Model: Big Gunner Caliber: 8.6 Blackout Firearm Fit: AR10 Length Range: 16"-20" Material: 4150 Steel Finish: Salt Bath Nitride Barrel: Type Button Rifled Twist: 1:3" Length: 16" Diameter: .875" Thread Pattern: M18X1.5 Barrel Description: Target Crown Steel Weight: 2.20 lbs