CMMG Banshee MK57 5.7x28 Micro AR Pistol, 5-inch Threaded Barrel, Radial Delayed Blowback, Matte Light Gray BFT 05694
This CMMG MK57 Banshee is a compact 5.7x28 AR-pattern pistol built around CMMG's radial delayed blowback system and a dedicated MK57 lower that accepts FN Five-seveN pistol magazines. It features a 5-inch 4140 chrome-moly barrel with a salt-bath nitride finish and 1/2x28 threads, a matte light gray 7075-T6 aluminum receiver set, and CMMG's Fastback brace system for rapid deployment. The package is in as-new condition and includes the factory box, manual, and one 20-round magazine. BFT 05694
Condition
Overall Condition: As-new condition with no signs of prior handling beyond what’s typical from inspection (see photos).
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: There are minimal markings from previous handling. Please refer to the photos for additional detail.
What’s Included
- CMMG factory box
- CMMG Firearm Safety and Basic Operation manual
- One 20-round FN Five-seveN-pattern 5.7x28 steel magazine
The MK57 lower is purpose-built to run 5.7x28, accepting FN Five-seveN pistol magazines for a compact footprint with a stated 20+1 capacity. Magazine witness marks at 5, 10, 15, and 20 rounds make it easy to verify load status at a glance.
The 5-inch barrel is 4140 chrome-moly steel with a salt-bath nitride finish for durability, cut with a 1:9 twist, and threaded 1/2x28 for compatible muzzle devices. The free-float aluminum M-LOK handguard keeps weight down and provides modern accessory mounting options.
CMMG's radial delayed blowback action is paired with a forged 7075-T6 upper and a billet 7075-T6 lower, both finished in matte light gray. The upper includes a right-side ejection port with dust cover and brass deflector, and it omits a forward assist. An integral trigger guard is machined into the lower.
The Fastback brace system allows quick deployment and includes adjustable length, a QD sling socket, and a hook-and-loop strap. Controls include a manual safety and an ambidextrous charging handle with an extended latch for easy manipulation.