Cmmg Banshee 57A340Fab Mk57 57X28 8 Brc Arblk

The CMMG Banshee Mk57 in 5.7x28mm is a modern AR-pattern pistol built around a platform purpose-designed for this emerging defensive cartridge. With an 8-inch barrel, the Banshee harnesses the full potential of 5.7x28 ballistics in a compact, maneuverable package ideal for close-quarters personal defense. If you're drawn to the flat-shooting, low-recoil characteristics of 5.7x28 but want AR ergonomics and controls, the Mk57 platform delivers both—and it does it without sacrificing the familiar features that make modern rifles so reliable.

The radial delayed blowback operating system keeps the Banshee running clean and controllable. The billet aluminum upper and forged lower receivers are built tough, while the CMMG EML7 M-LOK handguard gives you mounting flexibility for lights, lasers, or other modern accessories. You get last-round bolt hold-open, an ambidextrous charging handle, and a 60/90-degree safety selector—conventional AR functionality that shouldn't have to be sacrificed just because you're running pistol magazines. The included 20-round Promag magazine keeps capacity respectable while maintaining Five-seveN-pattern magazine compatibility, so you've got options in the field.

The CMMG ZEROED Linear Compensator mitigates muzzle rise without unnecessary blast signature, and the RipBrace stabilizer keeps the platform solid in your hands. At 5.2 pounds and 23.7 inches overall, the Banshee balks at neither carry nor control. This is a purpose-built 5.7x28 platform for shooters who want AR reliability and modularity in a caliber that's gaining traction with serious defensive shooters.

Key Features

• AR-pattern Mk57 platform chambered in 5.7x28mm for low recoil and flat trajectory
• 8-inch 4140CM barrel with 1:9 twist rate optimized for the cartridge
• Radial delayed blowback system for clean operation and reliability
• Accepts FN Five-seveN–pattern magazines; ships with 20-round Promag
• Last-round bolt hold-open and other conventional AR functionality intact
• Billet 6061-T6 aluminum upper receiver and forged 7075-T6 aluminum lower
• CMMG EML7 M-LOK handguard for modern accessory mounting
• Ambidextrous ZEROED charging handle and 60/90-degree safety selector
• CMMG ZEROED Linear Compensator (1/2 x 28 thread)
• CMMG RipBrace for stable, controlled handling
• Standard Cerakote finish

Specifications

Frequently Asked Questions

What magazines does the CMMG Banshee Mk57 accept?

The Banshee is built around the Mk57 platform and accepts FN Five-seveN–pattern magazines. The pistol ships with a 20-round Promag magazine, but you can use other compatible 5.7x28 magazines designed for the Five-seveN platform.

Is this a suitable personal defense firearm?

The Banshee Mk57 is purpose-designed as a personal defense weapon in 5.7x28mm. The 8-inch barrel is tuned to maximize the ballistic potential of this cartridge at close-range defensive distances, and the compact, light design makes it maneuverable for that role.

Does this pistol have an arm brace?

Yes, the Banshee comes equipped with the CMMG RipBrace, which provides a stable platform for controlled operation.

What's the weight and size of this gun?

The Banshee Mk57 weighs 5.2 pounds and measures 23.7 inches overall in length, making it a compact, portable platform despite its AR-pattern construction.