Griffin ATM (Advanced Threaded Match) Barrels are billet machined from 416R chromium stainless steel to exacting tolerances for the ultimate in drop in match performance. 5 axis machining done in a single work holding positions all critical dimensions on the breech ensuring theoretically perfect geometrical relationship of barrel slide and locking lug. Chambers are honed and polished to ensure an extremely smooth surface finish and optimal reliability with a wide range of ammunition from training to duty ammo. Two years of research and testing provided the appropriate knowledge to machine the barrel dimensions for a perfect fitment; providing the best possible accuracy without sacrificing factory reliability. Designed with concealed carry users in mind this barrel gives you the utility of accessory and suppressor support while providing uncompromising reliability.