Free Shipping & Free Returns*

FREE SHIPPING on Over 250,000 Products

Shop now and get Free Value Shipping on most orders over $49 to the contiguous 48 states, DC, and to all U.S. Military APO/FPO/DPO addresses.

Enjoy our FREE RETURNS

We want to ensure that making a return is as easy and hassle-free as possible! If for any reason you are not satisfied with your purchase, simply return the item within 30 days of receipt, and we'll cover the cost of return shipping. Learn more about our Return Policy.

Shopping Cart
Government Export Restriction Government Export Restriction
Government Restriction Government Restriction
Questions & Answers
Can you tell me if this will work with a Special Ops Tactical Disintegrater-9 handguard? Expert Answer

The CMMG Mk4/AR15 Upper Receiver Assembly might work with that handguard. However, I recommend contacting the manufacturer of your handguard to confirm compatibility with this upper receiver.

by Hunter, Gear Expert, December 7, 2022
Will this work on any standard ar15 lower receiver or are there bug difference between this and a mildpec upper. Thanks Expert Answer

The CMMG Mk4/AR15 Upper Receiver Assembly is compatible with any Milspec AR15 lower receiver assembly.

by Ethan, Gear Expert, February 23, 2023
Customer Reviews
Helpful Positive Review
Sniper Grey slick side upper by Hoang, Verified Owner, March 21, 2025
Quality is amazing, matches my aero precision m4e1 lower in sniper grey.
1/1 found this helpful
Helpful Positive Review
Review of CMMG Mk4/AR15 Upper Receiver Assembly by Tony, Verified Owner, May 4, 2024
This is the second CMMG upper I've purchased. The first one was for a Mk17 build. I was not impressed with the Cerakote finish. That'ssomething CMMG needs to do. I hoping the new was is better. I built a MKG glock Pistol with my new upper. I haven't...
Read More...
1/1 found this helpful
Helpful Positive Review
CMMG Mk4 Upper by Fb, Verified Owner, July 12, 2022
This is an excellent upper receiver. Fit nice and snug on my lower receivers. Matches great with my Noveseke billet lower. Also, it matches perfectly with my SLR Helix handguard. The profile looks like they were built to match. If you have a han...
Read More...
3/3 found this helpful
Helpful Negative Review
High quality, terrible specs by John L, Verified Owner, May 3, 2023
Bought one of these uppers for a build. Quality is top notch, worthy of 4-5 stars. We will see how the polymer brass deflector holds up. No forward assist plus the polymer makes this thing extremely light. Problems come though with how it is spec'd. ...
Read More...
5/6 found this helpful
Most Recent Reviews
The upper is lightweight, the shell deflector and dust cover are plastic, no forward assist. I found out the Midwest industries handguard with tangs that go around the sides of the upper are not compatible due to the thickness of the upper, a trip to...
Read More...
Most Recent Reviews
cmmg mk4/ar15 by Alan Barry, Verified Owner, December 18, 2024
Fits great haven’t went to the range yet but I expect it to run well
0/1 found this helpful
Read All 11 Reviews
Show In Stock Only
7 Models Available
Color
All
Muzzle Device
All
Search

ATTENTION! We currently do not ship this product to P.O. Boxes, AK, CA, CT, DE, HI, MA, NJ, NY, U.S. Territories, or select Colorado locations. Please see our policies for more information or a detailed list of locations.

Product Info for CMMG Mk4/AR15 Upper Receiver Assembly

Expertly crafted from aircraft grade aluminum, CMMG Mk4/AR15 upper receiver assemblies come with our ZEROED Polymer Dust Cover pre-installed. Available in six different Cerakote finishes, this upper receiver omits the forward assist for those looking for a sleek and stylish base to start a new AR15 build.image

WARNING: California`s Proposition 65

Specifications for CMMG Mk4/AR15 Upper Receiver Assembly:

Manufacturer: CMMG
Finish: Cerakote
Fabric/Material: Forged 7075-T6 Aluminum
Gun Make: CMMG, AR Platform
Gun Model: CMMG Mk4, AR-15
Magazine Included: No
Condition: New

Package Contents:

  • CMMG Mk4/AR15 Upper Receiver Assembly

CMMG Mk4/AR15 Upper Receiver Assembly Orderable Models

List of Orderable Models

  • CMMG Mk4/AR-15 Upper Receiver Assembly, Armor Black, 55BA290-AB , MPN: 55BA290-AB , UPC: 810097506329 , Code: 2CM-URC-CMAR415-55BA290-AB
  • CMMG Mk4/AR15 Upper Receiver Assembly, Sniper Grey, 55BA290-SG , MPN: 55BA290-SG , UPC: 810097506367 , Code: 2CM-URC-CMAR415-55BA290-SG
  • CMMG Mk4/AR15 Upper Receiver Assembly, Titanium, 55BA290-TI , MPN: 55BA290-TI , UPC: 810097506374 , Code: 2CM-URC-CMAR415-55BA290-TI
  • CMMG Mk4/AR15 Upper Receiver Assembly, Charcoal Green, 55BA290-CG , MPN: 55BA290-CG , UPC: 810097506336 , Code: 2CM-URC-CMAR415-55BA290-CG
  • CMMG Mk4/AR15 Upper Receiver Assembly, Tungsten, 55BA290-TNG , MPN: 55BA290-TNG , UPC: 810097506381 , Code: 2CM-URC-CMAR415-55BA290-TNG
  • CMMG Mk4/AR15 Upper Receiver Assembly, Coyote Tan, 55BA290-CT , MPN: 55BA290-CT , UPC: 810097506343 , Code: 2CM-URC-CMAR415-55BA290-CT
  • CMMG Mk4/AR15 Upper Receiver Assembly, Midnight Bronze, 55BA290-MB , MPN: 55BA290-MB , UPC: 810097506350 , Code: 2CM-URC-CMAR415-55BA290-MB

CMMG Mk4/AR15 Upper Receiver Assembly Unavailable & Discontinued Models

List of Unorderable Models

  • USED, CMMG Mk4/AR15 Upper Receiver Assembly, Tungsten, 55BA290-TNG , MPN: 55BA290-TNG-EDEMO , Code: 2CM-URC-CMAR415-55BA290-TNG-EDEMO-IN-C
  • USED, CMMG Mk4/AR-15 Upper Receiver Assembly, Armor Black, 55BA290-AB , MPN: 55BA290-AB-EDEMO , Code: 2CM-URC-CMAR415-55BA290-AB-EDEMO-IN-U
  • USED CMMG Mk4/AR-15 Upper Receiver Assembly, Armor Black, 55BA290-AB, EDEMO1, Used, Condition Like New , MPN: 55BA290-AB-EDEMO1 , Code: 2CM-URC-CMAR415-55BA290-AB-EDEMO1
  • DEMO, CMMG Mk4/AR15 Upper Receiver Assembly, Midnight Bronze, 55BA290-MB , MPN: 55BA290-MB-DEMO , Code: 2CM-URC-CMAR415-55BA290-MB-DEMO
Compare (0)
Last updated 2026-08-04 UTC.