CMMG Banshee Mk4 SBR (8" .300 Blackout)

The CMMG Banshee Mk4 SBR in 8" .300 Blackout is the cheapest factory .300 BLK short-barreled rifle with a real warranty pipeline behind it. CMMG's pistol-length gas system on the 8-inch barrel is the entire reason this platform exists: it's tuned at the factory to cycle both subsonic 220-grain suppressed loads and supersonic 110-125 grain defensive ammo without an adjustable gas block. That single engineering choice puts it in direct competition with $2,500+ piston guns from Sig and Q for the suppressor-host role, at roughly half the price.

The 8" 4140CM barrel runs a salt-bath nitride finish — internal and external corrosion resistance on par with chrome lining at a lower weight penalty. CMMG threads the muzzle 5/8x24, which is the correct .30-caliber standard and accepts any direct-thread or QD .30-cal suppressor without an adapter. The RML7 M-LOK 7-inch handguard floats the barrel and gives a clean accessory layout for a light and a sling mount; the skeletonized lower trims weight to ~5.5 lbs total, which rivals premium .300 BLK SBRs that cost two to three times as much.

The Banshee Mk4 is sold as a Form 4 SBR with a real stock, not a brace. The federal making/transfer tax on suppressors and SBRs was zeroed under OBBBA effective 2026-01-01, but registration, fingerprints, and NICS still apply — Form 4 wait times on the eForm pipeline are running days to a couple of weeks. Stock trigger is functional rather than match-grade and 8" supersonic .300 BLK falls off past 100 yards, but neither limitation matters for the role this rifle is built for: a suppressed, sub-6-pound house gun or truck gun where the suppressor and the ammo, not the barrel, do the work.