CMMG Banshee MK57 5.7x28mm 8-inch Threaded Barrel 20+1

About this product

Chambered for 5.7x28mm, the CMMG Banshee MK57 pairs a compact 8-inch threaded barrel with a Radial Delayed Blowback operating system for controlled, reliable cycling. Built on the MK57 platform, it accepts FN Five-seveN pattern magazines and ships with a 20-round ProMag magazine. The rifle-style controls and a full suite of CMMG ZEROED parts make this platform suitable for short-range defensive use and disciplined range work.

Key Specifications

• The chamber is configured for 5.7x28mm.
• The barrel measures 8 inches (Black Nitride, medium-taper) and is threaded.
• The action uses a Radial Delayed Blowback operating system.
• The barrel has a 1:9 twist rate.
• The muzzle is threaded 1/2 x 28 and includes a CMMG ZEROED linear compensator.
• The upper is machined from billet 6061 T6 aluminum and the lower is Mk57 forged 7075 T6 aluminum.
• Features a EML 7-inch M-LOK handguard for accessory mounting.
• Includes a full kit of ZEROED components and a CMMG ZEROED 60/90 Degree safety.
• Ships with a 20-round ProMag magazine and accepts FN Five-seveN pattern magazines.
• The firearm weighs 5.2 lbs and measures 23.7 inches overall.

Well-suited for compact defensive setups and dedicated range sessions, the Banshee MK57 balances compact handling with a clear parts pedigree and adaptable ergonomics. Its combination of low-mass footprint, standardized controls, and modular mounting options makes it a practical choice for users who prioritize dependable function and straightforward customization.

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