CMMG RESOLUTE Mk4 6.5 Grendel Rifle

The CMMG RESOLUTE Mk4 is a 6.5 Grendel AR-platform rifle (CMMG part no. 64ACFB8-AB) built for shooters who want more reach than 5.56 without stepping up to a larger-frame gun. The 6.5 Grendel cartridge was designed from the ground up for AR-15-pattern rifles like this one, delivering a flatter trajectory and more retained energy at medium to long range than standard carbine calibers. CMMG outfits the RESOLUTE with its curated ZEROED parts package for improved ergonomics and finishes it with the signature RIPSTOCK for a rifle that never feels out of place, whether at the range or in the field. The EML 15 M-LOK handguard cuts weight while keeping M-LOK slots at the 3, 6, 9, and 12 o’clock positions for mounting lights, grips, and other accessories. For shooters who find full-size rifles cumbersome but still want serious long-range ballistics, the RESOLUTE Mk4 fills that gap in a carbine-length package.

Key Specifications

• Chambered in 6.5 Grendel, a flat-shooting round designed specifically for AR-15-pattern rifles.
• Fitted with the adjustable CMMG RIPSTOCK for a consistent cheek weld and length of pull.
• Uses the EML 15 M-LOK free-float handguard with slots at 3, 6, 9, and 12 o’clock for accessory mounting.
• Comes equipped with CMMG’s curated ZEROED parts package for improved ergonomics and control feel.
• Built as a carbine-length AR-platform rifle, keeping handling quick despite the longer-range cartridge.

Frequently Asked Questions

What is the RESOLUTE Mk4 chambered in? It’s chambered in 6.5 Grendel, a cartridge built to deliver flatter trajectories and more energy at range than typical carbine calibers.

What handguard does it use? It uses CMMG’s EML 15 M-LOK handguard, which reduces weight while keeping mounting slots at the 3, 6, 9, and 12 o’clock positions.

Buy the CMMG RESOLUTE Mk4

Shooters who want 6.5 Grendel’s reach in a carbine-length package should take a close look at the RESOLUTE Mk4. Order it from CMMG‘s lineup at Schaefer Defense, browse our full AR rifle selection, and we’ll ship it insured to your local FFL from our Lubbock, Texas shop.