| Platform | Mk4, Mk57 |
| Caliber | 5.7x28mm |
| Operating System | Radial Delayed Blowback |
| Barrel Length | 16.1 |
| Barrel Twist | 1:9 |
| Barrel Contour | MT |
| Barrel Material | 4140CM, SBN |
| Barrel Twist | 1:9 |
| Muzzle Device | CMMG ZEROED Muzzle Brake |
| Muzzle Thread | 1/2 x 28 |
| Gas Port Location | N/A |
| Gas Block | N/A |
| Upper Receiver | Billet 6061 T6 Aluminum |
| Hand Guard | CMMG EML15 M-LOK |
| Finish | Cerakote Standard |
| Charging Handle | CMMG ZEROED Ambi |
| Weight | 4.0 lbs |
| Length | 25.3" |
Due to high demand and supply chain issues affecting many industries, some of our parts and accessories may be on backorder and have an extended lead time. Items currently on backorder can still be purchased and can typically be shipped within 25 business days.
UPPER GROUP, RESOLUTE, 5.7X28MM, 16.1"
Personal defense calibers like 5.7x28mm have become a big thing in the last few years, and if you’re looking for PDW ballistics and the classic style and balance of a carbine then you’re in luck. Combine this RESOLUTE® Upper Group with either our Mk57 Lower or a standard AR15 lower group and CMMG®’s 5.7 AR Conversion Magazines and you’ll be ready to hit the range! Available in seven different Cerakote finishes, all CMMG® Upper Groups come complete with bolt carrier group and ZEROED™ accessories including:
ZEROED AR15 Polymer Dust Cover
ZEROED AR15 Ambi Charging Handle
Radial Delayed Blowback™ Operating System
Originally developed for the .45 ACP MkG platform, CMMG has adapted our Radial Delayed Blowback system across our pistol caliber lineup to create pistols and rifles with a softer recoil impulse and reduced bolt weight compared to traditional straight blowback systems. Check out our CMMG Resources article & video to learn more about what sets Radial Delayed Blowback apart.
We aim to please, that’s why every CMMG product is backed by our Lifetime Quality Guarantee against material and workmanship defects. Learn More.