CMMG Banshee Mk4 SBR (8" .300 Blackout)

The CMMG Banshee Mk4 SBR in 8" .300 Blackout is a factory short-barreled rifle with current CMMG product support rather than a Form 1 parts build. The current Mk4 listing uses an 8-inch 4140CM SBN medium-taper barrel, pistol-length gas, and an adjustable .750 gas block, giving buyers a current .300 BLK SBR path with a real warranty pipeline behind it.

The 8" 4140CM barrel runs a salt-bath nitride finish for corrosion resistance, with 5/8x24 muzzle threads for standard .30-caliber direct-thread and QD suppressor mounts. CMMG's current configuration uses the EML7 M-LOK handguard, ZEROED drop-in trigger, B5 Systems Bravo stock, Magpul 30-round PMAG, billet 6061 upper, and Mk4 forged 7075 lower. Weight is listed at 5.2 pounds with a 24-inch overall length.

The Banshee Mk4 is sold as an SBR with a real stock, not a brace. All NFA rules still apply, including required registration and ATF processing. Supersonic .300 BLK falls off quickly compared with rifle cartridges, but that limitation fits the role: a compact, suppressor-ready, sub-6-pound .300 BLK host where the suppressor and ammunition choice do most of the work.