CMMG Banshee MK4 5.7x28mm 8" Barrel Extended Armor Black

The CMMG Banshee MK4 5.7x28mm pistol brings AR-15 platform versatility to a caliber engineered for modern personal defense. With an 8-inch barrel and radial delayed blowback operating system, this compact 5.7x28mm AR pistol delivers rifle-like ballistics with controllable recoil in a package that tips the scales at just 4.6 pounds. Built on CMMG's Mk4 platform using a standard AR-15 lower receiver, the Banshee uses CMMG's own 5.7x28mm conversion magazines—no proprietary lower needed, which means you can leverage your existing AR knowledge and parts inventory.

This isn't a rifle wearing a pistol's badge; the Banshee is purpose-built for shooters who want modularity without compromise. The billet 6061 T6 aluminum upper and forged 7075 T6 aluminum lower receiver are both dressed in Cerakote Armor Black finish. The CMMG EML7 handguard spans the full length with M-LOK slots on both sides and bottom, plus M-LOK between top Picatinny rail sections, giving you genuine flexibility to mount lights, lasers, or other must-have gear. Whether you're setting it up for home defense, range work, or testing the 5.7x28mm cartridge before committing to a larger platform, the modular design means you're not locked into a single configuration.

Every control—charging handle, pistol grip, trigger guard, safety selector, and drop-in trigger—is CMMG's own ZEROED component line, built to the same standard as the rest of the gun. The ZEROED linear compensator manages recoil and muzzle rise without excessive blast, while the ambidextrous charging handle and 60/90-degree safety selector make the Banshee friendly to left- and right-handed shooters alike. At 23.7 inches overall with a carbine buffer system and pistol tube receiver extension, this is a serious contender for anyone exploring 5.7x28mm as a personal defense platform.

Key Features

• 5.7x28mm caliber with rifle-like ballistics and reduced recoil
• 8-inch 4140CM SBN barrel with 1:9 twist rate
• Radial delayed blowback operating system for consistent reliability
• Mk4 AR-15 platform—uses standard AR-15 lower receivers and CMMG 5.7x28mm conversion magazines
• Billet 6061 T6 aluminum upper and forged 7075 T6 aluminum lower receiver
• CMMG EML7 M-LOK handguard with full-length mounting slots
• CMMG ZEROED linear compensator with 1/2 x 28 threads
• Ambidextrous ZEROED charging handle and 60/90-degree safety selector
• CMMG ZEROED drop-in trigger and trigger guard
• 32-round CMMG magazine included
• Cerakote Armor Black finish
• Carbine buffer system with pistol tube receiver extension
• Lightweight at 4.6 lbs; compact at 23.7 inches overall

Specifications

Frequently Asked Questions

Will this work with standard AR-15 lower receivers?

Yes. The CMMG Banshee MK4 is built on the Mk4 AR-15 platform and uses a standard AR-15 lower receiver, so it's compatible with lowers you may already own. The key is using CMMG's 5.7x28mm conversion magazines—no proprietary lower required.

What magazines does the Banshee MK4 use?

The Banshee MK4 uses CMMG's own 5.7x28mm AR conversion magazines. A 32-round magazine is included with this model.

Is the charging handle ambidextrous?

Yes. The CMMG ZEROED ambidextrous charging handle works for both left- and right-handed shooters, and the 60/90-degree safety selector is also reversible for either hand.

What's the purpose of the linear compensator?

The CMMG ZEROED linear compensator helps manage recoil and muzzle rise while directing gases forward rather than up or to the sides, reducing blast direction toward nearby shooters or walls. It's threaded 1/2 x 28 in case you want to swap it for a suppressor or other muzzle device.

How does the 5.7x28mm round compare to other pistol calibers?

The 5.7x28mm was designed to deliver rifle-like ballistics with less recoil than traditional pistol caliber carbines. In a dedicated AR-style platform like the Banshee, it offers a different performance envelope for shooters interested in exploring this modern defensive cartridge.