MPN: 0011100089


  • Caliber: .300 Blackout
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver: Seekin Precision NX15 Upper - CNC Machined From Solid 7075-T6 Billet Aluminum
  • Handguard: 7" Seekin Precision NOXs M-LOK Handguard - CNC Machined From 6061-T6 Aluminum
  • M4 Feed Ramps: Yes
  • Muzzle Device: Seekins Precision Melonited Nest Flash Hider
  • 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 lb. 4.3 oz.
  • Length: ~16.65"


  • AR-15


Would you like to have a weapon that's accurate, light, and comfortable to shoot? Well, you could use a 300 Blackout complete pistol upper that's very portable, concealable, and has enhanced capabilities. If you choose to build a whole new gun, a Seekins 300 Blackout complete pistol upper puts you more than halfway there. Seekins has put this upper together right, using match grade components that you would choose for yourself.. Seekins Precision is committed to producing high-quality parts for the AR platform. Begun in 2005 by an avid hunter and firearms user, the company maintains its status as one of the leading providers of firearm parts to this day.

What Is Inside The Seekins Precision 300 Blackout Complete Pistol Upper

Starting with a true match grade 8-inch 300 Blackout barrel that can shoot a tighter MOA that many shooters can manage. All the barrels produced by Seekins are machined from the finest stainless steel blanks and are given no less than four inspections to ensure their quality and accuracy. This 300 Blackout upper SBR is then treated to M4 feed ramps. If you're not familiar with those, they're simply feed ramps that are machined further to better feed ammo reliably. Seekins backs these up with an M-16 design bolt carrier group. This style BCG carries more mass and a longer, heavier firing pin that many shooters prefer simply for durability. However, this design allows you to fire full auto if you're so blessed with a license to do so. Then add 5 separate machined in anti-rotation QD mount points and what more could anyone want?

The NX Series .300 Blackout NX8 upper includes the Seekins Precision NX15 upper receiver. This Seekins billet upper is CNC-machined from 7075-T6 billet aluminum for maximum strength. The included 7” NOXs M-LOK handguard is extremely lightweight and infinitely adaptable because of it's M-LOK system. This makes the upper is perfect for tactical use. Both the receiver and the handguard feature a Type III Hardcoat Anodized matte black finish.

The NX8 also includes an adjustable gas block that allows you to tune your gas system for maximum performance. The gas system components are all coated with Melonite to resist corrosion and wear. Melonite coatings are also easier to clean than the standard Parkerized finishes.

You Can Have A 300 Blackout Upper SBR without Getting A New Gun

Of course, if you already have an 5.56 SBR that has the perfect trigger and furniture configuration for you, then you get a break. You simply remove your guns takedown and pivot pins. And your 5.56 can be changed into a whole new animal by adding this 300 Blackout upper SBR. A Seekins 300 blackout is a beautiful, deadly addition to anybody's bucket list.

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