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

Guns Of Shanghai F
Guns Of Shanghai F

The Guns of Shanghai 1937: A Prelude to WWII's Brutal Urban Combat

Often overlooked by Western military historians, the Battle of Shanghai in 1937 was an early sign of the brutal urban combat that would characterize much of World War II. An incredible array of arms was used in the fighting.

New For 2026: Vortex Strike Eagle 1-10X 24 mm FFP LPVO Riflescope

Previously offered in 1-6X and 1-8X variants, new for 2026, Vortex is introducing the Strike Eagle 1-10X 24 mm FFP riflescope.

Gun of the Week: Ruger RXM

On the surface, the RXM appears to be similar to the Glock G19-inspired selection of striker-fired, polymer-frame pistols on the market, but a closer look reveals that there's much more to this modular design.

Rifleman Q&A: How Frequently Should You Clean?

AN NRA member and his brother have identical rifles. One brother cleans every time he shoots. The other cleans every 100 rounds. Which barrel will last longer?

The Armed Citizen® March 20, 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.

NRA Launches New Official App

The National Rifle Association proudly unveiled its new official NRA App today, marking a significant milestone in enhancing member engagement and delivering convenient access to essential NRA resources on the go.

Interests



Get the best of American Rifleman delivered to your inbox.