CM15 300BLK 8″ 1:5 Twist Upper with Options

AR15 Upper | CM15 300BLK 8″ 1:5 Twist Upper with Options

CM15 300 BLK 8″ AR15 Upper

• CM 6061 lightweight billet aluminum receiver
  • Reliefs featured throughout the receiver
  • Picatinny rail milled channel for a sleek/light weight option
• CM 6061 7.25″ MLOK handguard
  • QD Sockets at 3 and 9 o’clock
  • Full Picatinny top rail
• Choice of Suppressor Host Muzzle Device or Thread Protector
• CM15 Low Mass Bolt Carrier Group
  • 9310 Hardened Steel Bolt
  • 17-4 Stainless Steel Firing Pin
  • 8620 Carrier and Key
  • MPI Tested
  • Hardened Extractor S7 Steel
• CM15 Warhammer Ambidextrous Charging Handle – in collaboration with Breek Arms
• Superlative Arms Adjustable Gas Block
• CM Melonite Gas Tube
• CM15 300 BLK 8″ Barrel
  • 416R Stainless Steel
  • Medium Profile
  • Black Cerakote
  • 1:5 Twist, 5R Rifling
  • Pistol Gas
  • .750 Gas Journal
  • 5/8×24 threaded muzzle

CM15 300BLK 8″ AR15 Upper: The Gold Standard for PDW Performance

The CM15 300BLK 8″ Upper represents the “sweet spot” of the .300 Blackout world. While 5-inch barrels are ultra-compact and 16-inch barrels are full-sized, the 8-inch configuration is widely considered the ballistic ideal for this caliber. It provides enough dwell time for reliable cycling and optimal velocity while remaining incredibly light and maneuverable in tight spaces.

The Power of the 1:5 Twist

To truly master the .300 Blackout, you need the right rotation. Our 1:5 ultra-fast twist rate is specifically engineered to stabilize heavy, high-BC subsonic rounds that slower twists simply can’t handle. This ensures that your heavy-grain projectiles fly true and expand as designed, making it the perfect choice for suppressed hunting or home defense applications where accuracy is paramount.

Built to Your Specifications

Like all CM15 uppers, this model is available with customizable options. Whether you need a tucked-suppressor look with an extended handguard or a lightweight M-LOK rail for essential accessories, we build it to your mission requirements.

Key Highlights:

• 8” Match-Grade Barrel: Optimized for full powder burn and maneuverability.

• 1:5 Twist Rate: Superior stabilization for heavy subsonic and supersonic loads.

• Reliable Cycling: Pistol-length gas system tuned for suppressed and unsuppressed use.

The CM15 8″ Upper is the ultimate foundation for a high-performance professional build that balances size and lethality perfectly.