CMMG Mk57 Banshee 5.7x28 AR Pistol, 5.25 in Threaded Barrel, Radial Delayed Blowback, Matte Gray
This CMMG Mk57 Banshee in 5.7x28mm pairs a compact 5.25-inch threaded barrel with CMMG's radial delayed blowback system and a dedicated Mk57 lower that feeds from FN Five-seveN-pattern magazines. It features a matte gray finish, a full-length 1913 Picatinny top rail, and a free-float aluminum handguard with M-LOK-style slots. An ambidextrous extended charging handle, adjustable stabilizing brace, and Magpul MOE pistol grip round out a well-configured AR-pattern pistol with a stated 20+1 capacity.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: Light finish marks from handling are present, with no notable blemishes.
What’s Included
- 1x 20-round 5.7x28 magazine (brand/model not specified)
- Single-point bungee sling with snap-hook attachment
The Mk57 Banshee lower is purpose-built for 5.7x28mm and accepts FN Five-seveN-pattern pistol magazines. This configuration offers a compact footprint with a stated capacity of 20+1, and a semi-automatic-only SAFE/SEMI selector.
The 5.25-inch barrel is threaded and includes a thread protector, making it easy to configure with compatible muzzle devices. A free-float aluminum handguard with M-LOK-style slots provides modern mounting flexibility while keeping weight forward under control.
A full-length 1913 Picatinny rail bridges the upper receiver and handguard, offering uninterrupted space for sights or accessories. The pistol is delivered without sights installed.
Controls and furniture are practical and well-appointed, including an ambidextrous extended charging handle, a manual safety selector, a loop-type sling end plate for snap-hook/HK-style attachment, a Magpul MOE pistol grip, and an adjustable stabilizing brace with a hook-and-loop strap.
The upper and lower receivers are aluminum with a matte gray finish, and the pistol is made in the United States. The radial delayed blowback action is tuned for the 5.7x28 cartridge, balancing reliability with a compact AR-15-pattern platform.