User Ratings
No ratings yet
Be the first to review this product
Upper receiver group for 5.7x28mm AR platforms. 8-inch upper with Armor Black finish. Designed to work with CMMG Mk57 lowers or standard AR-15/Mk4 lowers when used with 5.7x28mm AR mags. Built to maximize compactness and reliability for 5.7x28mm builds.
Specifications
- Manufacturer:
- Cmmg
- Category:
- upper-receiver
- Platforms:
- AR-15
- Length:
- 8.0"
- UPC:
- 810097504387
- MPN:
- 57B88BDAB
- Required Component:
- Yes
Parts Cabinet
Track parts you own or plan to buy.
Where to Buy
Have one to sell?
Sponsored
MantisX
The smart way to train your AR build
Built your rifle — now train it. BlackBeardX installs in minutes and turns your AR into a full dry fire system with smart feedback on every pull.
Shop BlackBeardXPrice History
Current
$829.99
Lowest
$829.99
Highest
$829.99
Price Alert
Sign in to save a target price and receive an email when this component drops.
Sign In to Set AlertBundle Package
This is a bundled product that includes multiple components. The exact contents may vary - check the product description for more details.
• Complete assembly ready to use
• Multiple components included
• Value package pricing
Similar Products
Bravo Company BCM4 Upper Receiver Assembly Flat Top With Forward Assist 1913 Rail
Bravo Company Manufacturing (BCM)
$129.00
Aero Precision AR15 Assembled Upper Receiver - Anodized Black - APAR501603AC
Aero Precision
$118.99
LMT Monolithic Upper Receiver - AR-15 - MRP-L - M-LOK - Specwar - 11.5"
LMT
$912.60
Griffin Armament Mk1 Upper Receiver Assembled Aluminum Black
Griffin Armament
$113.95
BCM MK2 Carbine Barreled Upper MCMR-10 - 12.5in
Bravo Company Manufacturing (BCM)
$820.39
AERO PRECISION - 5.56X45 NATO ASSEMBLED UPPER RECEIVER NO AUTO SEAR CUT FOR AR-15
Aero Precision
$119.99
COLT Monolithic AR-15 Pistol Complete Upper Receiver 5.56x45 NATO 11.5" Barrel
Colt
$959.99
Luth-ar UR-01-M16-A A1 Upper Receiver 223/5.56mm Aluminum Black Hardcoat Anodize
Luth-AR
$180.69
Builds Using This Part
No builds yet — be the first to use this part.
Related Guides
Guide
5.56 NATO, .223 Remington, and .223 Wylde: Chamber Differences Explained
A technical breakdown of the differences between 5.56 NATO, .223 Remington, and .223 Wylde chambers — what each accepts safely, and how to choose for your build.
5 min read
Guide
AR-10 Receiver Patterns: DPMS vs. Armalite Compatibility
The AR-10 has two incompatible receiver patterns — DPMS and Armalite — that look similar but do not share parts. This guide explains the differences and how to buy correctly.
6 min read
Guide
The AR-10 Platform: What It Is and How It Differs from the AR-15
A practical overview of the AR-10 — its origins, how it differs from the AR-15, available calibers, and when it makes more sense than a standard AR-15 build.
6 min read