| Platform | Mk4, Mk57 |
| Caliber | 5.7x28mm |
| Operating System | Radial Delayed Blowback |
| Barrel Length | 8 |
| Barrel Twist | 1:9 |
| Barrel Contour | MT |
| Barrel Material | 4140CM, SBN |
| Barrel Twist | 1:9 |
| Muzzle Device | CMMG ZEROED Linear Compensator |
| Muzzle Thread | 1/2 x 28 |
| Gas Port Location | N/A |
| Gas Block | N/A |
| Upper Receiver | Billet 6061 T6 Aluminum |
| Hand Guard | CMMG EML7 M-LOK |
| Finish | Cerakote Standard |
| Charging Handle | CMMG ZEROED Ambi |
| Weight | 2.9 lbs |
| Length | 16.5" |
Due to high demand, some of our parts and accessories may be on backorder and have an extended lead time. Items currently on backorder can still be purchased. Expected to ship in 4 to 6 weeks.
UPPER GROUP, BANSHEE, 5.7X28MM, 8"
Designed to provide superior ballistics and less felt recoil than most pistol caliber personal defense weapons, 5.7x28mm has quickly become one of the most popular chamberings in the PDW space. With the 8” BANSHEE™ upper group you can build the PDW AR15 of your dreams. Compatible with either CMMG® Mk57™ lowers or a standard AR15/Mk4 lower (when used with CMMG 5.7 AR Conversion Mags). Available in 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
ZEROED Linear Compensator 5.56mm
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.