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Customer Reviews
Helpful Positive Review
Great upper by TK, March 26, 2024
This CMMG upper is lightweight and the finish is great.
1/1 found this helpful
Most Recent Reviews
Unsatisfied by Steven Rodriguez, Verified Owner, May 26, 2026
Paid an additional $9.99 for expedition shipping, so got it a whopping 1 day earlier. Box looked like someone rode it to my house. The bubble wrap inside the box was mostly popped, but CMMG always has a hard plastic packaging around the item you buy....
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Most Recent Reviews
ao far so good by Ricky, April 23, 2025
Seems to be good quality and came fast when I needed it .. it was sent off to get painted and assembled and when I finally get to put rounds through it I’ll let you know
Most Recent Reviews
tightest upper i have ever seen by G3 Dimitri, Verified Owner, April 19, 2025
Absolutely shocked about how nice this thing is, crazy tight tolerances. Cerekote had zero flaws and feed ramps were machined perfectly. Will grab more for future builds.
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Product Info for CMMG Mk4/AR15 Upper Receiver Assembly w/Forward Assist

Whether its the classic style or forward assist functionality that piques your interest, the Mk4 AR15 upper receiver assembly has been a staple in the CMMG lineup. Available in six different Cerakote finishes, this mil-spec workhorse has been proven over the years and makes a great base to build your next AR15 upper group.image

WARNING: California`s Proposition 65

Specifications for CMMG Mk4/AR15 Upper Receiver Assembly w/Forward Assist:

Manufacturer: CMMG
Barrel Profile: M4
Fabric/Material: 7075 T6 Aluminum
Gun Make: CMMG
Gun Model: CMMG Mk4
Magazine Included: No
Condition: New

Package Contents:

  • CMMG Mk4/AR15 Upper Receiver Assembly w/Forward Assist

CMMG Mk4/AR15 Upper Receiver Assembly w/Forward Assist Orderable Models

List of Orderable Models

  • CMMG Upper Receiver Assembly, Mk4/AR15, Forward Assist, Coyote Tan, 55BA206-CT , MPN: 55BA206-CT , UPC: 810097506411 , Code: 2CM-URC-CP53-55BA206-CT
  • CMMG Upper Receiver Assembly, Mk4/AR15, Forward Assist, Tungsten, 55BA206-TNG , MPN: 55BA206-TNG , UPC: 810097506459 , Code: 2CM-URC-CP53-55BA206-TNG
  • CMMG Upper Receiver Assembly, Mk4/AR15, Forward Assist, Sniper Grey, 55BA206-SG , MPN: 55BA206-SG , UPC: 810097506435 , Code: 2CM-URC-CP53-55BA206-SG
  • CMMG Upper Receiver Assembly, Mk4/AR15, Forward Assist, Titanium, 55BA206-TI , MPN: 55BA206-TI , UPC: 810097506442 , Code: 2CM-URC-CP53-55BA206-TI
  • CMMG Upper Receiver Assembly, Mk4/AR15, Forward Assist, Charcoal Green, 55BA206-CG , MPN: 55BA206-CG , UPC: 810097506404 , Code: 2CM-URC-CP53-55BA206-CG
  • CMMG Upper Receiver Assembly, Mk4/AR15, Forward Assist, Midnight Bronze, 55BA206-MB , MPN: 55BA206-MB , UPC: 810097506428 , Code: 2CM-URC-CP53-55BA206-MB
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Last updated 2026-11-11 UTC.