CMMG MK4 PDW Upper Receiver 300 Blackout 8″


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SKU: RS-CMMG30B8188 Categories: , ,


The Mk4 PDW Upper Group is CMMG’s smallest, most compact upper group equipped with the RKM7 KeyMod free floating hand guard and a nitrided 4140 CrMo steel barrel. Every upper group is covered by CMMG’s lifetime quality guarantee.

*Please be advised that our system will prevent products from being shipped to locations where they are prohibited by law. Both your billing and shipping address must be located in an area where these items are not prohibited*

  • Caliber: 300 Blackout
  • Barrel: 8.0”, 1:7 twist, medium taper, 4140CM, SBN
  • Muzzle: A2 comp., threaded 5/8-24
  • Hand Guard: CMMG RKM7 KeyMod hand guard
  • Receiver: Forged 7075-T6 AL M4 type upper
  • Gas Port Location: Pistol

Upper Group consists of:

  • Upper Receiver Assembly (Upper Receiver, Ejection Port Cover, Forward Assist)
  • Barrel Sub-Assembly
  • Hand Guard and Barrel Nut Charging Handle Bolt Carrier Group

Additional information

Weight 92.805793971187 oz
Barrel Length





No additional specifications are currently available.

MSR Arms Advisor

The MSR Arms Advisor articles are intended to answer some of the most common shooter questions and assist our customers in making the best purchasing decision possible. There are currently no articles available for this item. If you would like help selecting the right part for your needs, please email our sales team at:


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