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CMMG
Overview
The CMMG MK/4 AR-15 Upper Receiver Assembly is a stripped upper designed specifically for the AR-15 platform, allowing builders the flexibility to customize their setup according to their preferences. Finished in a sleek black color, this upper receiver provides a solid foundation for your build, ensuring compatibility with a variety of components. It's commonly found in builds featuring a carbine gas system and chambered for .308 Win, making it a versatile choice for those looking to enhance their firearm's performance.
Specifications
October 2026 on GunPartPicker
CMMG MK/4 AR-15 Upper Receiver Assembly Armor Black ranked #87 of the 844 upper receivers builders added on GunPartPicker in October 2026. Builders have added it to their builds on GunPartPicker. Since April 2026, it ranks #102 of the 2,051 upper receivers builders have added. Builds with this upper receiver are mostly chambered in 5.56 NATO (60%, then 300 Blackout 25%), split between mid-length (56%) and carbine-length (22%) gas systems, and nearly all AR-15.
It was in stock most times we checked in October 2026, and today 2 of the 3 retailers we track have it in stock. Prices barely moved in October 2026, holding around $136.99, with no real sale all month. Buying today, the lowest price is $137.99 at Palmetto State Armory.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 37 retailers
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Frequently Built With
The part most often added in each category by the builds that include this one
Bravo Company Manufacturing 16" SS410 5.56 NATO 1:8 Mid-Length AR-15 Barrel - IonBonded Black
Radian Weapons AR-15 Raptor SD-SL Ambidextrous Charging Handle Black
WMD Guns AR-15 Gas Tube Nitromet Mid-Length
Magpul MOE M-LOK Handguard, Rilfe, Gray
AR-15 Kp-15 Complete Lower Receivers Mil-Spec Polymer - AR-15 Kp-15 Complete Lower Receiver Mil-Spec Polymer Black
PSA AR-15 Bolt Carrier Group 5.56 Full-Auto Nitride MPI - 516446953
Build Configuration Breakdown
Aggregated and anonymized data showing how builders use this product
CaliberBased on real build data showing which calibers builders choose alongside this product.
Gas SystemBased on real build data showing which gas system lengths builders use with this product.
Builds Featuring This Part
See all builds →Builds in the community that include the CMMG MK/4 AR-15 Upper Receiver Assembly Armor Black
| Build | Parts | Total |
|---|---|---|
 | 20 | $821.79 |
 | 24 | $6450.14 |
 | 27 | $6963.05 |
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