Range Review: CMMG Mk57 Banshee in 5.7x28 mm

posted on July 24, 2018

Before we get into the details behind the new CMMG Mk57 Banshee chambered in 5.7x28 mm, put on your wayback cap. Go all the way back to January 2018. SHOT Show, to be specific. Walking the show floor, we stopped into the CMMG booth. These folks are always good for something new and unique, whether it be tactical bacon in a can, an AR-15-style rifle in .45 ACP or even a massive .458 SOCOM beast. This year, they did not disappoint when showing us their latest creation chambered in 5.7x28 mm.

So 5.7x28 mm? The round originally conceived for the FN America P90, the super-duper space gun developed for NATO in the Reagan years as the PDW di tutti PDW? That round? The one ballistically similar to .22 Mag. but in a centerfire round? That round? Yep, the one and the same. When asked why CMMG’s next efforts were in the 5.7x28 mm round, CMMG Product Development Manager Tyson Bradshaw responded, “The 5.7x28 mm was chosen for its low recoil, lightweight ammunition and flat trajectory compared to other pistol calibers. It’s also a very capable defensive round.”

There’s no question the 5.7x28 mm round is low recoil and easy to shoot—just watch the video above. Keeping an AR-15-size pistol on target at 50 yards with the 5.7x28 mm is just plain stupid-easy. The ballistic arc is superior to other pistol calibers, and muzzle energy is comparable. In more-simple terms, it flies straighter than 9 mm or .45 ACP but still hits hard at defensive distances. But, even more than that, recoil is so low as to be negligible, so that follow-up shots are easy and new shooters don’t balk at the noise and kick.

The reduced felt recoil on the CMMG Mk57 Banshee pistol isn't just due to the cartridge choice, though. The company added in its innovative Radial Delayed Blowback system first used in the MkG Guard carbine chambered in .45 ACP. In short, this feature means that the Mk57 Banshee can use a lighter-weight buffer and bolt carrier than blowback-only designs, reducing the amount of traveling weight that contributes to felt recoil.

More than anything, though, it’s just plain fun. It’s something different; it’s good to see CMMG thinking outside traditional AR chamberings for the company’s latest offering in the Banshee line-up. Of course, all the standard Banshee features are included in this latest model, including M-Lok-compatible handguards, radial-delayed blowback for superior operation and CMMG’s single-stage trigger. The Mk57 Banshee pistol is available with the Gear Head Works Tailhook Mod 2 brace or a KAK Shockwave brace, and the SBR version has CMMG’s proprietary RipStock retractable buttstock.

CMMG will be offering lightweight buffers for use with subsonic ammunition, and all Mk57 guns ship with 20-round ProMag magazines. The Banshee is also compatible with FN 5.7 pistol magazines. Magpul MOE grips and, for the SBR, MVG foregrips come as standard components on this new model. All barrels are threaded in the standard 1/2x28 TPI thread pitch, and come with thread protectors as standard equipment.

Four different models are offered in the new Mk57 lineup. The first two models are part of CMMG's Banshee collection and can be had in either SBR or pistol configurations. Each gun is equipped with a 5-inch barrel machined from 4140 chrome-moly steel and featuring a twist rate of 1:9 inches. The SBR and pistol are both equipped with CMMG's single-stage mil-spec trigger and are equipped with the company's RML4 handguard complete with a hand stop. With the stock or brace collapsed, the overall length of the design is 18.5 inches long. Those who opt for the SBR variant will have their gun outfitted with CMMG's innovative RipStock, which can be deployed without depressing a release lever. The pistol model is equipped with a Tailhook Mod 2 stabilizing brace from Gear Head Works. 

Other options in the Mk57 collection are the CMMG Mk57 Guard PSB pistols. This model offers a slightly longer barrel, measuring in at 8 inches and featuring the same profile and construction as the Banshee guns. The barrel is topped with a CMMG A2 Compensator rather than a thread protector, and the gun itself is outfitted with the company's RML7 handguard, providing a few more inches of rail space versus the RML4 on the Banshee. CMMG also opted to add on a KAK Shockwave brace on this design, but consumers can opt for the model that features no stabilizing brace at all at a reduced MSRP.

Suggested retail pricing starts at $1,349.95 on the Mk57 Guard PSB pistol and ends at $1,549.95 for both of the Mk57 Banshee guns.


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