CMMG Banshee MK4 8 Inch Semi-Automatic Firearm

Description

The Banshee MK4 is built around the premise of a compact, pistol-caliber platform that shares its manual of arms with any standard AR15. That compatibility matters in practice: anyone already trained on an AR15 lower transitions without relearning controls, and existing PMAG inventory can be converted to feed 9mm rounds through CMMG’s 9mm AR conversion adapters rather than requiring a dedicated magazine system.

The MK4 designation means this Banshee rides on a standard AR15-pattern lower receiver rather than a proprietary frame, which keeps the aftermarket wide open for grip modules, triggers, and lower parts. The CMMG Zeroed ambidextrous safety selector operates at 60 and 90 degrees, giving left- and right-handed shooters consistent access without a separate installation step. The EML handguard runs full-length M-LOK slots along both sides and the underside, with additional M-LOK real estate between the top Picatinny rail sections — so light, pressure switch, and sling mount placement are not constrained by the handguard geometry.

Because the platform runs 9mm from a blowback or radial-delayed system rather than a rifle gas impingement arrangement, the felt impulse character differs from a centerfire rifle: the action cycles on chamber pressure rather than a timed gas port, which affects how the muzzle tracks during rapid strings. The optics-ready upper leaves the top rail uncluttered so the shooter can mount whatever red dot or magnified optic suits their intended distance. The RIPBRACE deploys quickly and adds a rear contact point without adding significant length when stowed.