The CMMG Resolute Mk4 Semi-Auto Rifle is a well-built AR-15. Built around a billet 6061 upper and forged Mk4 lower, the Resolute Mk4 Rifle features a traditional direct-impingement system with an adjustable gas block that allows you to fine-tune the performance. The 4140 CmV steel barrel features a salt bath nitride finish and comes topped with a muzzle brake that reduces felt recoil. For those who want better-than-mil-spec performance off the shelf, the Resolute Mk4 comes with a full suite of CMMG's own ZEROED components. The ZEROED drop-in trigger features a single-stage pull, 4-4.5 lb. pull weight, and short reset. The ZEROED 60/90 safety selector and ZEROED charging handle allow for fully ambidextrous operation. The Resolute Mk4 Rifle is a fully loaded AR-15 with top-tier components right out of the box. Includes one 10-round magazine. Billet 6061 upper and forged 7075 lower Direct-impingement operation with adjustable gas block 4140 CmV steel barrel with muzzle brake ZEROED single-stage trigger with 4-4.5 lb. pull weight ZEROED 60/90 ambidextrous safety selector ZEROED ambidextrous charging handle