CMMG Unveils the First 5.7x28mm to .22LR Conversion Kit

Read AmmoLand’s live-fire review of the CMMG Bravo 22LR AR Conversion Kit and video here.

CMMG Unveils the First 5.7x28mm to .22LR Conversion Kit
CMMG Unveils the First 5.7x28mm to .22LR Conversion Kit

U.S.A.-( CMMG expands on the popular .22LR Conversion Kit with the addition of the Mk57 .22LR AR Conversion Kit. Easily convert your CMMG 5.7x28mm upper receiver group into a .22LR by swapping the bolt-carrier group, paired with the 5.7x28mm upper and any Mil-Spec AR15/Mk4 lower receiver, while using a dedicated CMMG .22LR magazine.

CMMG prides itself on caliber flexibility. The ability to shoot multiple calibers with one lower has its obvious advantages. One firearm, reduced cost, muscle memory, and storage to name a few.

The Mk57 .22LR Conversion Kit is designed to be used with all CMMG Mk57 5.7x28mm upper receiver groups and bolt/barrel combinations when paired with any Mil-Spec AR15/Mk4 lower receiver. CMMG offers Mk57 5.7x28mm complete uppers in 5-inch, 8-inch, and 16-inch barrel lengths.

Converting any CMMG Mk57 upper to shoot .22LR is a great way to reduce cost with each pull of the trigger, all while reducing recoil and muzzle flash. Anyone who is interested in 5.7x28mm. but concerned about ammo prices, can take advantage of cost-effective rimfire training. It’s the ultimate tool for young or first-time shooters.

Mk57 .22LR Conversion Kits come with a dedicated bolt-carrier group and the choice of one or three 25rd magazine(s) with an MSRP of $199.95 to $229.95.

For States with magazine capacity restrictions, the Mk57 .22LR Conversion Kit can be purchased with 10rd magazines.

For more information on the Mk57 .22LR Conversion Kit, please visit

CMMG Guarantee:

All CMMG products are covered under the CMMG Lifetime Quality Guarantee. Conditioned on being a Limited Warranty of use, maintenance, and cleaning of the product in accordance with CMMG, Inc.’s instructions to be free of defects in material and workmanship. CMMG will repair, replace or substitute part(s) as determined in the sole and absolute discretion of CMMG Inc at no charge to the purchaser or provider. Complete limited warranty information can be found at

About CMMG:CMMG logo

CMMG began in central Missouri in 2002 and quickly developed into a full-time business because of its group of knowledgeable and passionate firearms enthusiasts committed to quality and service. Its reputation was built on attention to detail, cutting edge innovation and the superior craftsmanship that comes from sourcing all their own parts. By offering high quality AR rifles, parts and accessories, CMMG’s commitment to top-quality products and professional service is as deep today as it was when it began.

For more information, visit

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I don’t understand all the hype about this caliber. All it is is a glorified 22LR. People keep saying it is like a 223. It is no where near it. A 223 is 5.7 x 57, a 22LR is 5.7 x 26, and this ammo is 5.7 x 28. To me that means it is a heck of a lot closer to a 22LR then a 223.


Yeah, ok:

Prior to this Covid 19 craziness I had planned on getting one of the Ruger 57 handguns. I figured the price would come down after all the “got to have one of the new guns” people had bought theirs. I have thousands of once fired cases and the dies to load them.

I also use the fired cases to make .308 caliber rifle bullets. They work very well in my 308 Win and 30-06.