The CMMG Resolute MK4 5.56 Barreled Upper Receiver is designed for precision and durability, featuring a 16.1″ Chrome Moly barrel with a medium contour and a 1:7 twist rate. The barrel is made from 4140 chrome moly steel coated with a salt bath nitride finish for corrosion resistance, while the mid-length gas system ensures smoother operation and recoil management. This RESOLUTE Mk4 Upper Group is chambered in 5.56x45mm NATO and comes ready to pair with the AR15 lower group of your choice.
The upper is machined from billet 6061-T6 aluminum with a durable black Cerakote finish, paired with the CMMG EML15 M-LOK handguard for added customization options. M-LOK attachment slots are found at the 3, 6, and 9 o’clock positions as well as on top at 12 o’clock, which reduces weight while still giving shooters a place to mount accessories. The 1/2×28 threaded muzzle is equipped with an A2 muzzle device, helping reduce flash signature and improve follow-up shots. With a total weight of just 3.6 lbs and an overall length of 25 inches, this upper receiver provides excellent balance and maneuverability.
This 5.56 RESOLUTE is built on the Mk4 platform and accepts virtually any and all AR15 accessories. This upper group does not include BCG or charging handle, allowing you to customize your build to your exact specifications. Every CMMG product is backed by the company’s Lifetime Quality Guarantee against material and workmanship defects.
