CMMG Complete 16" M4 LE Upper .300 Blackout

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CMMG Complete 16" M4 LE Upper .300 Blackout


  • Caliber: 300 Blackout
  • Barrel: 16.1″, 1:7 twist, multi-role, 4140CM, SBN
  • Muzzle: A2 comp., threaded 5/8-24
  • Hand Guard: M4 type 2-piece hand guard
  • Receiver: Forged 7075-T6 AL M4 type upper
  • Gas Port Location: Carbine
  • Made in USA

The CMMG Mk4LE OR 300 BLK Upper Receiver Group is chambered for the 300 AAC Blackout (7.62x35mm) cartridge. It features a 16", M300 profile, 4140 chrome-moly steel barrel. A salt bath nitrided finish is applied to the barrel inside and out for improved wear, abrasion, and corrosion resistance.

The Mk4LE comes with an M4 hand guard. The barrel of the CMMG Mk4LE OR 16-inch .300 Blackout Upper Receiver Group has a 1:7" twist, and the muzzle utilizes an A2 compensator with a 5/8"-24 thread.