CMMG's Mk3 CBR .308 Win. Upper Group features a 16" medium-taper barrel made of 416 stainless steel with a nitrided finish. 1:10 rate of twist. It's also equipped with CMMG's SV muzzle brake and a RKM15 KeyMod handguard. Receiver constructed of solid 6061-T6 aluminum billet for lasting performance. Made in USA.