The CMMG Banshee MK4 in 5.7x28mm is an ultra-compact AR-style pistol designed for close-range use on the range and for compact handling scenarios. With a short 5-inch barrel and a high-capacity 40+1 configuration, it delivers the compact form factor and magazine capacity sought in a modern AR pistol.

Built on CMMG’s Mk4 AR15 platform, this Banshee features a Black Nitride medium taper threaded barrel and a durable Midnight Bronze Cerakote aluminum finish. The EML4 handguards provide M-LOK attachment points and an integrated handstop, while the receiver includes a full-length Picatinny top rail for optics and accessories. The firearm ships with CMMG Zeroed grips and is compatible with AR conversion magazines as specified by the manufacturer.

Key Specifications

The caliber is 5.7x28mm.
The barrel length is 5 inches.
The capacity is 40+1.
The barrel finish is Black Nitride.
The handguards are EML4 M-LOK with slots at the 3, 6, and 9 o’clock positions.
The receiver features a full-length Picatinny top rail.
The finish on aluminum components is Midnight Bronze Cerakote.
The pistol includes CMMG Zeroed grips.
The handguards include an integrated handstop.
The platform is built on the Mk4 AR15 design and uses a standard AR15 lower receiver.