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CMMG has unveiled its Mk57 Guard line of AR pistols and SBRs chambered in FN 5.7x28mm.

This series comes in five-inch-barreled Banshee and eight-inch-barreled PSB setups. The Banshee in FN 5.7×28 is available either as a SBR or an AR pistol. The SBR variant comes with a Magpul MOE vertical foregrip and includes CMMG’s RipStock, which lets users extend the stock out with having to use a release lever. It also has five set-screw positions that let users change up the length of extension to ensure an optimum fit. The AR pistol Banshee versions come with a Gear Head Works Tailhook Mod2 brace. In addition, the Banshee also includes CMMG’s ambi charging handle; RML4 M-LOK handguard; and a CMMG Premier Cerakote finish, with 11 different colors to choose from. It ships with one 20-round ProMag magazine and is compatible with FN Five-SeveN pistol mags.

Meanwhile, the Mk57 PSB features an eight-inch barrel; KAK Shockwave Brace; CMMG RML7 M-LOK handguard; and a CMMG A2 Compensator. The pistol variant has the same features, but it doesn’t come with the brace. Like the Banshee, both models come with one 20-round ProMag magazine and are compatible with FN Five-SeveN pistol magazines.

Radial Delayed Blowback

Every version of the Mk57 Guard uses CMMG’s Radial Delayed Blowback system. More on that system below, via the press release:

At the heart of the Mk57 is CMMG’s Radial Delayed Blowback operating system designed to minimize felt recoil. It features rotating bolt that requires the recoil impulse of a round being fired in order to unlock. As each round is fired, a portion of the rearward force is exhausted in unlocking this bolt prior to driving the carrier rearward and cycling the action. With less rearward force to compensate for, CMMG is able to use a lighter carrier and buffer than a standard blowback design would allow, thus reducing the overall reciprocating mass.

FN 5.7x28mm

In addition, here’s a primer on the FN 5.7x28mm cartridge, again from CMMG’s press release:

The FN 5.7×28 was designed and introduced by FN Herstal with the intention of replacing the 9mm for military and law enforcement usage. While the caliber has been adopted by several agencies throughout the world, its real success came with its entry into the civilian market in the early 2000’s.

“The 5.7 is an intriguing round that is perhaps best known for its relatively lightweight bullet design and impressive velocities. From an engineering perspective, we were excited to pair the 5.7 with our Radial Delayed Blowback system. I think it’s safe to say that this combination makes the Mk57 one of the lightest recoiling pistol caliber carbines on the market,” said Chris Reinkemeyer, CEO of CMMG.

MSRP on the Mk57 Guard ranges from $1,349.95 to $1,549.95, depending on the setup you choose. See the specs for each model below, along with a video on the Mk57 Guard.

For more on CMMG, visit cmmginc.com.

Mk57 Guard BANSHEE 5.7x28mm SBR

  • BARREL: 5″ MT 4140CM SBN, 1:9 Twist
  • MUZZLE: Thread Protector, Threaded ½-28
  • BCG WEIGHT: 9.9 oz.
  • HAND GUARD: CMMG RML4
  • FURNITURE: Magpul MOE Pistol Grip, Compact Receiver Extension, CMMG RipStock, Magpul MVG Foregrip, Fully Ambidextrous Sling Plate, Selector, and Charging Handle
  • RECEIVERS: Billet 7075-T6 AL Lower, Forged 7075-T6 AL Upper
  • TRIGGER: CMMG Single Stage Mil-Spec
  • MAGAZINE: 20-round ProMag
  • WEIGHT: 4.6 lbs (Unloaded)
  • LENGTH: 21.75″ (STOCK EXTENDED) 18.5″ (STOCK COLLAPSED)
  • MSRP: $1,549.95

Mk57 BANSHEE 5.7x28mm Pistol

  • BARREL: 5″ MT 4140CM SBN, 1:9 Twist
  • MUZZLE: Thread Protector, Threaded ½-28
  • BCG WEIGHT: 9.9 oz.
  • HAND GUARD: CMMG RML4
  • FURNITURE: Magpul MOE Pistol Grip, Gear Head Works Tailhook Mod 2 Brace, Fully Ambidextrous Sling Plate, Selector, and Charging Handle
  • RECEIVERS: Billet 7075-T6 AL Lower, Forged 7075-T6 AL Upper
  • TRIGGER: CMMG Single Stage Mil-Spec
  • MAGAZINE: 20-round ProMag
  • WEIGHT: 4.7 lbs (Unloaded)
  • LENGTH: 21.75″ (STOCK EXTENDED) 18.5″ (STOCK COLLAPSED)
  • MSRP: $1,549.95

Mk57 5.7x28mm PSB

  • Mk57 PSB 5.7x28mm Pistol
  • BARREL: 8″ MT 4140CM SBN, 1:9 Twist
  • MUZZLE: CMMG A2 Compensator, Threaded ½-28
  • BCG WEIGHT: 9.9 oz.
  • HAND GUARD: CMMG RML7
  • FURNITURE: Magpul MOE Pistol Grip, KAK Shockwave Stabilizer and Brace
  • RECEIVERS: Billet 7075-T6 AL Lower, Forged 7075-T6 AL Upper
  • TRIGGER: CMMG Single Stage Mil-Spec
  • MAGAZINE: 20-round ProMag
  • WEIGHT: 5 lbs (Unloaded)
  • LENGTH: 25″
  • MSRP: $1,399.95

Mk57 5.7x28mm Pistol

  • Mk57 PSB 5.7x28mm Pistol
  • BARREL: 8″ MT 4140CM SBN, 1:9 Twist
  • MUZZLE: CMMG A2 Compensator, Threaded ½-28
  • BCG WEIGHT: 9.9 oz.
  • HAND GUARD: CMMG RML7
  • FURNITURE: Magpul MOE Pistol Grip
  • RECEIVERS: Billet 7075-T6 AL Lower, Forged 7075-T6 AL Upper
  • TRIGGER: CMMG Single Stage Mil-Spec
  • MAGAZINE: 20-round ProMag
  • WEIGHT: 5 lbs (Unloaded)
  • LENGTH: 25″
  • MSRP: $1,349.95

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