Brand: CMMG
Model: Dissent
Caliber: .300 AAC Blackout
Platform: AR, Mk4
Barrel: 6.5" 4140CM, SBN
Color: Armor Black
Finish: Cerakote
Gas System: Pistol Length Compact Action-Direct Impingement
Muzzle Device: CMMG Zeroed Linear Compensator
Muzzle Thread: 5/8-24
Twist: 1:7
Receiver: Dissent 7075 T6 Aluminum
Handguard: CMMG 5.5" Proprietary
Attachment Style: M-Lok
BCG: Yes
Charging Handle: Dissent Side Charger, Left Side
Receiver Extension: 1913 Picatinny Rail End Cap

Features

DISSENT .300 Blackout Upper Group – Compact Power, Maximum Versatility

Unleash the power of .30 caliber in a compact PDW form with the .300 AAC Blackout DISSENT Upper Group. Built for seamless integration with your MK4 DISSENT lower or any standard AR-15 lower, this upper offers a bold mix of innovation, functionality, and refined design.

At the core is CMMG’s patent-pending Compact Action, a direct impingement system that houses the full action and recoil assembly within the upper receiver—eliminating the need for a traditional buffer tube. This allows for a shorter overall length and reduced bulk, perfect for modern AR pistol builds. The forward non-reciprocating side charger keeps bolt manipulation fast and smooth without breaking your sight picture.

Each DISSENT upper includes a 1913 Picatinny rail end plate, giving you the freedom to attach stocks or braces designed for Pic interfaces. With an adjustable gas block, you can easily fine-tune performance for either subsonic or supersonic loads, making it ideal for suppressed or unsuppressed setups.

Whether you're upgrading or starting fresh, the DISSENT .300 BLK Upper Group delivers compact firepower with precision and reliability built in.

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Shipping Restrictions

It is the customer’s responsibility for understanding state laws regarding all purchases made. For a comprehensive list of all Shipping Restrictions, please refer to our Shipping Restrictions By State Page found Here.

All NFA Rules Apply

These items are controlled by the U.S. Government and authorized for export only to the country of ultimate destination for use by the ultimate consignee or end-user(s) herein identified. They may not be resold, transferred, or otherwise disposed of, to any other country or to any person other than the authorized ultimate consignee or end-user(s), either in their original form or after being incorporated into other items, without first obtaining approval from the U.S. government or as otherwise authorized by U.S. law and regulations.

Local Law Compliance

Certain firearm parts and accessories, including AR-style upper receivers, are subject to complex and frequently changing federal, state, and local laws and regulations. While an upper receiver may be lawfully sold and shipped as a component, the legality of possessing, assembling, configuring, or using an upper receiver in certain states (e.g., California, Washington State) and localities depends on how it is assembled, combined with other components, and ultimately used. You are solely responsible for ensuring that any assembly, configuration, possession, or use complies with all federal, state, and local laws, including any so-called “assault weapon” bans and short-barreled rifle restrictions. We do not provide legal advice and are not responsible for unlawful configurations or uses.