The CMMG Resolute Mk4 Upper is a complete assembly chambered in 5.7x28mm for the AR-platform. It features a 16.1 4140 Chrome Moly steel barrel with a 1:9 twist rate and Salt Bath Nitride finish. The receiver is finished in Armor Black Cerakote and paired with a 15 EML15 M-LOK free-float handguard. This group includes a ZEROED Muzzle Brake (1/2x28 thread), a bolt carrier group, and a ZEROED Ambi Charging Handle. It is designed for seamless integration with standard AR-style lower groups.