The CMMG Resolute MK4 Upper Group (brand part number 60B1091AB) is chambered in 6mm ARC, designed to pair with any standard AR15 pattern lower group and harness the caliber’s efficient long-range ballistics in a 16.1-inch upper. Built by CMMG, this Direct Impingement upper ships complete with a bolt carrier group and CMMG’s ZEROED accessories, including a polymer dust cover, an ambidextrous charging handle, and a 6.5mm-pattern muzzle brake, all finished in Cerakote over a stainless steel barrel.

Key Specifications

• Chambered in 6mm ARC on the Mk4 platform.
• Barrel length is 16.1 inches.
• Operating system is direct impingement.
• Twist rate is 1:7.5, matched to 6mm ARC bullet weights.
• Barrel material is 416 stainless steel with a salt bath nitride finish.
• Muzzle device is a CMMG ZEROED muzzle brake, threaded 5/8×24.
• Gas system is rifle-length with a 0.750-inch non-adjustable gas block.
• Upper receiver is billet 6061-T6 aluminum with an EML15 M-LOK handguard.
• Includes a CMMG ZEROED ambidextrous charging handle and bolt carrier group.
• Weighs approximately 4.3 pounds with a 25-inch overall length.

Frequently Asked Questions

Does this upper include a bolt carrier group? Yes, all CMMG Upper Groups ship complete with a bolt carrier group and CMMG’s ZEROED accessories.

Will this fit a standard AR15 lower? Yes, it is designed to pair with any standard AR15 pattern lower group.

Buy the CMMG Resolute MK4 6mm ARC Upper Group

Add efficient long-range 6mm ARC performance to your AR15. Order this AR-15 upper from our Lubbock, Texas gun shop for fast, insured shipping to your door.