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

Kimber 1911 Ds Warrior Gotw 1
Kimber 1911 Ds Warrior Gotw 1

Gun of the Week: Kimber 1911 DS Warrior LW

In 2026, Kimber developed its 1911 DS Warrior, an American-made, double-stack design that is intended to be an affordable entry point into Kimber's double-stack handgun line.

The Armed Citizen® April 24, 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.

Spin Difference: The Impact of Barrel Twist Rates on Terminal Performance

When most shooters think of rifling-twist rates, they mostly think of rifles with their high BC projectiles, but the rpm of a bullet also plays a part in terminal performance.

Beretta's 1301 Tactical vs. A300 Ultima Patrol Shotguns: Which Should You Choose?

Ever since Beretta launched the A300 Ultima Patrol shotgun in 2024 as a less-pricey alternative to the 1301 Tactical, shotgunners have debated whether the 1301 is worth the extra cost. Let's examine them both.

ZEV Technologies Escaping Washington State’s Hostile Political Climate

ZEV Technologies announced it is moving its headquarters and manufacturing operations out of Washington state to Utah’s Second Amendment-friendly business climate.

U.S. v. Hemani Arguments

On March 2, the U.S. Supreme Court heard oral arguments in U.S. v. Hemani. The case involves a defendant who is fighting a federal indictment for possessing a firearm while being a marijuana user.

Interests



Get the best of American Rifleman delivered to your inbox.