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.