Easy to install drop-in design. Advanced proprietary broach cut design specifically engineered for increased accuracy potential. Broach cut 6 groove rifling allows for all ammo types to be used safely, including cast lead. 100% Designed and manufactured in the USA with USA sourced certified 416R stainless steel. 9mm 1/10RH twist rifling. Target style crown for non-threaded versions or 1/2x28 threads with included thread protector on threaded versions. Threaded versions include Viton high heat integral O-ring lock thread protector.