MPN: 0011100057


  • Caliber: .300 Blackout
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver: Seekin Precision iRMT Upper - CNC Machined From Solid 7075-T6 Billet Aluminum
  • Handguard: 12" Seekin Precision MCSRV2 M-LOK Handguard - CNC Machined From 6061-T6 Aluminum
  • M4 Feed Ramps: Yes
  • Muzzle Device: Not Included
  • Barrel: 8” 1:8 Match Grade 416 Stainless Steel 300BLK Barrel
  • Muzzle Thread Pattern: 5/8"-24
  • Gas Block: Seekins Precision Melonited Adjustable Gas Block
  • Gas Tube: Pistol-Length Melonited Gas Tube
  • Bolt Carrier Group: Seekins Precision Melonite Coated NX15 Bolt Carrier Group
  • Charging Handle: Seekins Precision DNA Charging Handle

*This upper receiver assembly has a barrel that is shorter than 16". This upper is only for use on AR pistol lower receivers and NFA registered Short-Barreled Rifle (SBR) lower receivers. All NFA laws apply!


  • Weight: ~3.52 lb.
  • Length: ~19.75"
  • Distance From Muzzle to Front of Handguard: ~10.62"


  • AR-15


For those who demand excellence in sports shooting, short-range competitions, or home defense, the Seekins Precision SBR8 .300 Blackout 8" Complete Upper Assembly is a top-tier choice.

Integrated and Modular Design

What sets the SBR8 apart is Seekins Precision’s innovative Integrated Rail Mounting technology (iRMT). This design cleverly integrates the rail mounting points into the upper receiver, maintaining stiffness while allowing for full modularity of the rails. The result is a more streamlined, efficient firearm.

Optimized for Suppressor Use

Designed with suppressor compatibility in mind, the SBR8 excels in scenarios where noise reduction is crucial. This makes it an ideal choice for quiet sport shooting or home defense situations where discretion is key.

Precision Engineering for Reliable Accuracy

The SBR8 features a 300BLK 8" barrel with a 1:8 twist, crafted from 5R 416 Stainless Steel, ensuring accuracy and durability. Paired with a 12" MCSR MLOK handguard and Seekins Low Profile Adjustable Gas Block, this assembly provides both stability and adaptability.

A Game Changer for Firearm Enthusiasts

Choosing the Seekins Precision SBR8 .300 Blackout 8" Complete Upper Assembly is more than an upgrade – it's a commitment to quality and performance. Whether you're engaged in competitive shooting or ensuring home safety, this assembly guarantees to elevate your shooting experience to the highest standards.

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