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

Franchi Momentum MULE rifle
Franchi Momentum MULE rifle

New for 2026: Franchi Momentum Mule Rifle

Franchi’s do-it-all MULE rifle is designed as a general-purpose carbine.

New for 2026: Smith & Wesson Spec Series M&P9 and R Handguns

Smith & Wesson expands its Spec series with the Spec Series IV M&P9 M2.0 Metal Compact pistol and the Spec Series R revolver.

New for 2026: Henry Provider and Protector Rifles

For 2026, Henry adds two new product families, one designed for hunting, the other for protection.

Gun Of The Week: Daniel Defense DDPCC 9 mm Carbine

Daniel Defense's pistol-caliber carbine, the DDPCC, offers AR-15-style operation in a more budget-friendly caliber.

The Armed Citizen® Jan. 23, 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.

New for 2026: Stoeger STR-45 Combat Pistol

For 2026, Stoeger adds the .45 ACP chambering to its Combat line of STR handguns.

Interests



Get the best of American Rifleman delivered to your inbox.