When modularity, affordability, and quality are all important, the CMMG Mk4 is the upper of choice. The Mk4 introduces CMMG's RKM series of KeyMod free float hand guards, as well as an 11 RKM hand guard and a nitrided 4140 CrMo steel barrel in a medium taper profile.

Features:

Forged 7075-T6 aluminum M4 type upper
Nitrided 4140 CM steel medium taper barrel
A2 compensator
CMMG RKM 11"" KeyMod free-float handguard
Caliber: .300 Blackout
Barrel Length: 16""
Barrel Twist: 1:7
Barrel Finish: Black
Barrel Fluting: None
Barrel Profile: Mid Weight
Firearm Fit: AR-15
Weight: 5.00 Lbs

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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.