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CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver Up to 16% Off w/ Free S&H — 4 models

CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Armor Black, 30BC239-AB
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Coyote Tan, 30BC239-CT
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Tungsten, 30BC239-TNG
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Midnight Bronze, 30BC239-MB
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Armor Black, 30BC239-AB
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CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Armor Black, 30BC239-AB
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Coyote Tan, 30BC239-CT
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CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Coyote Tan, 30BC239-CT
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Tungsten, 30BC239-TNG
3 of 4 images
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Tungsten, 30BC239-TNG
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Midnight Bronze, 30BC239-MB
4 of 4 images
CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Midnight Bronze, 30BC239-MB

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Questions & Answers
Does it come with the BCG?

Yes, it's included.

by LeeTN, Verified Owner, November 3, 2025
Is this compatible with standard milspec ARs? Also would the buffer tube be able to be uninstalled since it’s direct impingement?

First, a rifle's recoil system (buffer, tube, spring) has nothing to do with its operating system (DI, short-stroke piston, long-stroke piston); all kinds of combinations exist. Now, the Dissent's recoil system is housed entirely withing the upper receiver; it has no buffer tube. CMMG includes a 1913 (Picatinny) rail to be installled on a milspec lower where the buffer tube would normally be. You can use a folding brace or stock.

by LeeTN, Verified Owner, November 3, 2025
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Customer Reviews
Helpful Positive Review
Comes with something important by Will, Verified Owner, December 8, 2024
I am building my own bufferless 300-blk AR, and I ended up picking this over the BRN. One advantage with CMMG is that they include a buffer adapter that goes right where your traditional stock would go. Many companies try to sell you an adapter well ...
Read More...
2/2 found this helpful
Most Recent Reviews
CMMG DISSENT Mk4 300BLK 10.5 upper receiver by Sean, April 22, 2026
Excellent build quality as always from CMMG. Fit perfectly with an already existing AR lower and binary trigger. Now it’s a double tap machine!
Read All 2 Reviews
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Product Info for CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver

Many of you love the 6.5 300BLK DISSENT, so we decided to take it and crank it up to 11!... or how about 10.5? Giving you improved ballistics and an even more suppressor friendly length, this all new length 300BLK upper is just the ticket to finish your 300BLK AR pistol build.image

Its no secret that pistol stabilizing braces have been a target for scrutiny over the years, and those that enjoy building their own AR pistols have wondered what will come out of all the uncertainty. DISSENT is our answer. Utilizing our patent pending direct impingement Compact Action, DISSENT upper groups house the entire action and recoil assembly in the upper receiver resulting in less bulk and length than traditional AR pistols. The forward non-reciprocating side charger allows for quick bolt operation without coming off target.

DISSENT Upper groups include a 1913 Picatinny rail end plate to use in place of the lower receiver buffer tube.

Specifications for CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver:

Manufacturer: CMMG
Caliber: .300 AAC Blackout
Barrel Length: 10.5 in
Barrel Twist Rate: 1-7
Firearms Threads Per Inch: 5/8x24
Muzzle Device: Zeroed Linear Compensator
Finish: Cerakote
Fabric/Material: Aluminum
Gun Rail: M-LOK
Gun Make: CMMG
Gun Model: CMMG Mk4
Magazine Included: No

Package Contents:

  • CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver

What firearm models does the manufacturer say CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver is compatible with?

The manufacturer suggests that CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver is compatible with CMMG Mk4

CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver Orderable Models

List of Orderable Models

  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Armor Black, 30BC239-AB , MPN: 30BC239-AB , UPC: 810097509115 , Code: 2CM-URC-DS3105-30BC239-AB
  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Coyote Tan, 30BC239-CT , MPN: 30BC239-CT , UPC: 810097509153 , Code: 2CM-URC-DS3105-30BC239-CT
  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Tungsten, 30BC239-TNG , MPN: 30BC239-TNG , UPC: 810097509191 , Code: 2CM-URC-DS3105-30BC239-TNG
  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Midnight Bronze, 30BC239-MB , MPN: 30BC239-MB , UPC: 810097509160 , Code: 2CM-URC-DS3105-30BC239-MB

CMMG DISSENT Mk4, 300BLK, 10.5in Upper Receiver Unavailable & Discontinued Models

List of Unorderable Models

  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Anodized Black, 30BC239-HCA , MPN: 30BC239-HCA , Code: 2CM-URC-DS3105-30BC239-HCA
  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Sniper Grey, 30BC239-SG , MPN: 30BC239-SG , UPC: 810097509177 , Code: 2CM-URC-DS3105-30BC239-SG
  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Charcoal Green, 30BC239-CG , MPN: 30BC239-CG , UPC: 810097509122 , Code: 2CM-URC-DS3105-30BC239-CG
  • CMMG DISSENT Upper Receiver, Mk4, 300BLK, 10.5in, 1-7 Twist, 5/8x24 Thread, Zeroed Linear Compensator, Titanium, 30BC239-TI , MPN: 30BC239-TI , UPC: 810097509184 , Code: 2CM-URC-DS3105-30BC239-TI
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