The CMMG Resolute Mk4 in 5.7x28mm (MPN 54A3F0FCT) answers the growing demand for a personal-defense-weapon caliber built into the modular Mk4 AR-15 platform, using CMMG’s new generation of 5.7 magazines that fit standard AR-15 magwells instead of pistol magazines. CMMG runs a radial delayed blowback operating system through a 16.1-inch 4140 chrome-moly barrel with a 1:9-inch twist, threaded 1/2×28 for the CMMG ZEROED muzzle brake. The rifle carries a billet 6061-T6 aluminum upper over a forged 7075-T6 Mk4 lower, ambidextrous charging handle and ZEROED pistol grip, a drop-in trigger, and the CMMG RipStock on a 6-position Fastback receiver extension, finished in Coyote Tan. It feeds from a 32-round CMMG magazine. Among AR-platform rifles in the AR rifles category, the Resolute Mk4 favors shooters who want 5.7x28mm performance in a full-size AR-15 magwell format.

Key Specifications

• Chambered in 5.7x28mm with a 1:9-inch rate of twist.
• Built on a radial delayed blowback operating system.
• Features a 16.1-inch nitride-finished 4140 chrome-moly barrel.
• Upper receiver is billet 6061-T6 aluminum; lower is forged 7075-T6.
• Includes the CMMG ZEROED muzzle brake, threaded 1/2×28.
• The stock is the CMMG RipStock on a 6-position Fastback extension.
• The trigger is a CMMG ZEROED design.
• The pistol grip is a CMMG ZEROED component.
• Finished in Coyote Tan.
• Feeds from a 32-round CMMG magazine that fits standard AR-15 magwells.
• Weighs approximately 6.4 pounds, 32.5 inches overall.

Frequently Asked Questions

Why 5.7x28mm in an AR-15? CMMG’s magazine design fits standard AR-15 magwells, so this rifle doesn’t need dedicated pistol magazines.

What operating system does this rifle use? Radial delayed blowback, distinct from direct impingement.

What is the magazine capacity? A 32-round CMMG magazine.

Buy the CMMG Resolute Mk4 5.7x28mm, Coyote Tan

5.7x28mm performance in a full-size AR-15 magwell format is exactly what the Resolute Mk4 delivers. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL.