The CMMG RESOLUTE Mk4 6mm ARC Upper Group, 16.1-Inch (CMMG part no. 60B1091AB) is chambered in 6mm ARC and pairs with any standard AR15 pattern lower group. CMMG builds the 16.1-inch barrel with a 1:7.5 twist and fits it with a ZEROED SVB Brake threaded 5/8×24. The receiver is billet 6061 T6 aluminum with a CMMG EML15 M-LOK handguard and Armor Black Cerakote. It comes with a bolt carrier group and ZEROED accessories.

Key Specifications

• The chambering is 6mm ARC, the caliber this Mk4 upper is built around.
• The barrel length is 16.1 inches with a 1:7.5 twist and a medium taper contour.
• The barrel is 416 stainless steel with CMMG’s SBN finish.
• The muzzle device is a ZEROED SVB Brake, threaded 5/8×24.
• The operating system is direct impingement with a rifle gas port.
• The gas block is an adjustable 0.750-inch model for tuning the gas flow.
• The upper receiver is billet 6061 T6 aluminum, a light and rigid alloy.
• The handguard is a CMMG EML15 M-LOK, which accepts M-LOK accessories.
• The included charging handle is a CMMG ZEROED ambi model, with a ZEROED AR15 polymer dust cover.
• The upper group weighs 4.3 pounds and measures 25 inches long.

Frequently Asked Questions

What is included with this 6mm ARC upper? CMMG says its upper groups come complete with a bolt carrier group and ZEROED accessories, including the ZEROED AR15 polymer dust cover and the ZEROED AR15 ambi charging handle.

What lower does it fit? CMMG designed it to pair with any standard AR15 pattern lower group.

Does it have a muzzle brake? Yes. It has a ZEROED SVB Brake threaded 5/8×24.

Buy the CMMG RESOLUTE Mk4 6mm ARC Upper Group, 16.1-Inch, ZEROED SVB Brake, Armor Black

Switching to 6mm ARC is a matter of swapping the upper. See more AR-15 uppers from CMMG. Order from our Lubbock, Texas gun shop for fast, direct shipping.