CMMG Resolute Mk3 8.6 Blackout 16.1"

The CMMG Resolute Mk3 in 8.6 Blackout is the mainstream semi-auto host for the cartridge, a step up in fit, finish, and reputation from budget options without the four-figure premium of a Q Boombox. It is built on CMMG's Mk3 large-frame receiver, a DPMS-high pattern, and ships as a complete rifle with a 20-round PMAG in the box. The 16.1-inch barrel runs a 1:3 twist, the original fast-twist rate that stabilizes 8.6's heavy subsonic .338 projectiles; SAAMI's 2026 spec uses a 1:6 reference twist, but 1:3 is what most early 8.6 hardware runs.

CMMG has built large-frame ARs for years, and the Resolute line is its general-purpose rifle family. The 8.6 chambering brings that build quality to a suppressed-subsonic cartridge: thread a .338-rated can onto the muzzle, run subsonic 300-grain loads, and the rifle is hearing-safe on most hosts. It feeds from the standard SR-25 magazine pattern and uses a conventional .308 bolt face, so spares and accessories come from the established AR-10 ecosystem rather than a proprietary parts catalog.

This is the rifle for a buyer who wants 8.6 Blackout from a name they trust, is willing to pay roughly $1,950, and does not want to assemble an upper. The honest caveat is the cartridge itself: factory ammunition is scarce and expensive, so plan a suppressor purchase and a reloading setup alongside the rifle.