First Look: CMMG 5.7x28 mm AR Conversion

by
posted on January 15, 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. **
cmmg-inc-57x28mm-ar-conversion-magazine-upper-receiver-f.jpg
In 2020, the 5.7x28 mm cartridge is coming back in a big way, and CMMG joined multiple companies in offering a new option for fans of this high-velocity cartridge. Following up on the success of the company's Banshee chambered in 5.7x28 mm, CMMG now offers an AR-15 conversion package that allows shooters to mate their mil-spec AR-15 lower receiver with the company's 5.7x28 mm Radial Delayed Blowback upper-receiver group.

The key to this conversion lies in CMMG's 5.7 AR Conversion Magazine, which is designed to fit into standard AR-15 magazine wells while providing a reliable feed mechanism that's compatible with the company's 5.7x28 mm upper receiver. To convert any standard AR-15 to a 5.7 mm firearm, simply remove the existing upper-receiver group and replace it with a compatible, 5.7x28 mm upper receiver from CMMG. Once the upper receiver is installed, users can simply insert a CMMG 5.7 AR Conversion Magazine into the mil-spec magazine well.

In addition to allowing AR owners to experiment with the 5.7x28 mm cartridge without having to purchase an entirely new firearm, this CMMG conversion system maintains the controls and configuration of any existing AR-15 lower. If users have an enhanced trigger installed in their gun or optimized controls, they can continue using those components without having to invest in or learn an entirely new firearm. CMMG recommends the use of a standard carbine buffer and action spring to run the 5.7x28 mm conversion reliably, and the magazine provides last-round bolt hold-open capability.

A complete lineup of CMMG Banshee and Resolute upper receivers are compatible with the 5.7 AR Conversion Magazine. CMMG's Mk57 upper receivers can be had in 5", 8" and 16" barrel lengths, and the uppers ship complete with bolt-carrier group and charging handle. A single CMMG 5.7 AR Conversion Magazine holds 40 rounds of 5.7x28 mm, and the suggested retail price on the mag is $39.95. Suggested retail pricing on the Mk57 upper receiver complete with three 40-round magazines starts at $799.95. For more information on these conversion kits, visit cmmginc.com.


Latest

IHTOG Lee Metford 1
IHTOG Lee Metford 1

I Have This Old Gun: The British Lee-Metford Rifle

In the late 1880s, the British military adopted its first bolt-action rifle chambered for the .303 British cartridge. This is the Lee-Metford, the first step on the way to the iconic Lee-Enfield.

Colt Delivers M4A1 Rifles to Guatemala Through Foreign Military Sales Program

Guatemala’s military recently acquired more than 2,000 Colt M4A1 rifles through the U.S. government's Foreign Military Sales program as part of the country's ongoing military modernization efforts.

NRA Launches New Texas Senate Ad as Part of Multi-Million Dollar Campaign to Retain Pro-Gun Majorities in Congress

The NRA today released a new 30-second ad highlighting Democrat U.S. Senate candidate James Talarico’s longstanding support for banning so-called “assault weapons” and standard-capacity magazines—the firearms and accessories owned by millions of law-abiding Texans.

Going Pro: Springfield Armory's Echelon Pro Comp

Springfield Armory has expanded its Echelon line of handguns with several new Echelon Pro Comp offerings, bringing a number of what the company calls "performance-oriented enhancements" to the platform.

Steel Yourselves—Metal is Back

These days, it’s safe to say that injection-molded polymer of some sort is the most prevalent material from which to construct a pistol frame, but lately, that trend seems to be reversing. Metal is back.

NRA-ILA Names National Shooting Sports Foundation Official Partner of the 2026 NRA Gun Bus Battleground Tour

This sponsorship through NSSF’s Protect Liberty PAC puts the firearms industry trade association on the road through Election Day.

Interests



Get the best of American Rifleman delivered to your inbox.