CMMG Mk57 GUARD in FN 5.7×28
Boonville, MO – CMMG has announced the release of a new line of AR pistols and short-barreled rifles (SBR’s) chambered in FN 5.7x28mm. Available in 5-inch barrelled BANSHEE and 8-inch barrelled PSB configurations, each model in the new Mk57 GUARD line is fed from FN 5.7 pistol magazines and uses CMMG’s patent-pending Radial Delayed Blowback operating system.
“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.
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.
CMMG will also offer a separate lightweight buffer for use with subsonic ammunition. To overcome the reduced backpressure with subsonic loads, the lightweight buffer can help ensure that the bolt locks back after firing the last round.
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. Read more