Editor’s Choice: CMMG 5.7 mm Conversion Kit

by
posted on May 19, 2020
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
cmmgkit.jpg

CMMG has tapped into a cartridge that has long been a niche round for a select few enthusiasts: the 5.7x28 mm FN. The cartridge underwent a recent resurgence with the launch of the CMMG Mk57 Banshee in 2019 and received a bigger boost with the 2020 launch of the Ruger-57.

Now CMMG proves that it wasn’t finished with the 5.7 mm by rolling out a conversion kit for today’s AR-15 rifle owners. The Mk57 Banshee fed from Five-SeveN magazines, requiring added investment for anyone not already sitting on a stock of them.

However, the Mk57 AR Conversion Kit provides an opportunity for owners of mil-spec AR-15 lower receivers to get in on the 5.7 mm fun. The conversion 
includes a STANAG-size magazine that provides a reliable feeding platform for the company’s 5.7x28 mm FN upper receiver.

Best of all, these proprietary magazines hold 40 rounds each, providing twice the capacity of FN Five-SeveN pistol magazines. For more information on these CMMG 5.7 Conversion Kits, visit
cmmginc.com.

Latest

John Commerford
John Commerford

Political Report | America at 250: Celebrate Our History

It isn’t news to the patriotic members of the National Rifle Association that July 4, 2026, marks the 250th anniversary of the Declaration of Independence and the founding of the United States of America.

Benelli Updates Its M2 Field Shotgun

Over the years, Benelli shotguns have gotten subtle updates that have made their reliability and usability even better. New for 2026, Benelli’s M2 Field models are getting added features for better comfort and control.

It’s OK to Have Fun

A gun is a serious tool, but it can also be an object of joy.

Gun of the Week: Springfield Armory Model 2020 Boundary

While the company's initial Model 2020 Waypoint design was intended to be more of a precision platform, Springfield has since come out with several field-ready variants of the Model 2020, including the Boundary.

Standing Guard | The NRA and Freedom’s 250th

A quarter of a millennium ago this July 4, John Hancock was the first to sign the Declaration of Independence.

The Armed Citizen® June 19, 2026

Read today's "The Armed Citizen" entry for real stories of law-abiding citizens, past and present, who used their firearms to save lives.

Interests



Get the best of American Rifleman delivered to your inbox.