Blackout Defense AR-15 Performance Series barrels are excellent button-rifled barrels that are designed for performance. It is not unusual for customers of Blackout Defense Performance Series barrels to shoot 1 MOA or better in optimal conditions using match-grade ammunition and other quality components. The Performance Series barrels start with premium 416-R stainless steel bars that are gun-drilled and reamed at standard production speeds in 5R rifling and 1:8 twist. The blanks are then fully stress relieved and precision air gauged before profiling, threading, and chambering begins. Profiling and threading are completed on an ultra-precision 5-axis mill turn machine. The profile design includes three thermal expansion rings to limit distortion of the barrel during heavy use, as well as an extended gas block journal to accommodate enhanced gas blocks. The muzzle thread is machined to 1/2 28 with an 11-degree crown. The barrels are then chambered in .223 Wylde and individually inspected with a dummy round in addition to precision go and no-go gauges to ensure an accurate headspace. Finally, the barrels are hand deburred and polished to a consistent finish and salt bath nitrided for enhanced durability and corrosion resistance. The barrel extensions are separately nitrided, cleaned, and then installed to ensure a perfect torque.