Lifetime Warranty Lifetime Warranty Made in the USA Made in the USA FREE Shipping on $325+ Free Shipping on all orders $325+!

300 Blackout AR 15 Rifle Kit (10.5″ Stainless Barrel & 10″ M-Lok Handguard) w/ 80% Lower

$700.00 $550.00 (You Save $150.00)

Complete Build Kit - 300 Blackout (10.5" SS Barrel & 10" M-Lok Handguard) AR 15
Save For Later
Save For Later

Free Shipping on all orders $325+!

SKU: UA300PHB10.517(SS)-(10)MLOK_Budget


Our 10.5″ pistol upper chambered in .300 AAC blackout provides the perfect balance of compact profile and weight savings. The full-length M-LOK handguard is skeletonized, so it shaves off additional weight.  It offers some serious aesthetic appeal and provides plenty of rail space for attachments at the same time. A free-float design further improves accuracy.  It has a carbine gas system.  All these factors together mean this .300 blackout upper will reliably handle both supersonic and subsonic .300BLK loads. Topping it all off is an industry-leading 416R stainless barrel with a 1:7 twist rate to make this pistol-length upper assembly one of the most accurate .300 blackout uppers you’ll find in a pistol configuration.

The Most Accurate 300 Blackout Pistol Upper

The words “accuracy” and “pistol upper” don’t often go together, so we sought to fix that. We combined a best-of-both-worlds 10.5″ barrel length with a heavy profile and 416R stainless steel to offer the most accuracy possible. If there’s a .300 blackout pistol upper that might hit 1 MOA accuracy, you’re looking at it. Everything is manufactured under ISO 9002 quality control standards, and all rifling is CNC cut and heat-treated to a hardness rating of RC 28 to 32. This guarantees the most accurate barrel possible, with the most barrel life and wear resistance.

300 Blackout Pistol Barrel Features:

  • 300 AAC Blackout chamber
  • 10.5″ with polished finish
  • 416R stainless steel
  • Heavy profile
  • 1:7 twist rate
  • 5/8 x 24 thread pitch
  • A2 birdcage flash suppressor

300 Blackout Receiver Features:

  • 10″ free floating M-LOK handguard
  • Carbine-length gas system (0.125 Hole)
  • Low profile gas block (0.750)
  • M4 flat top upper
  • M4 feed ramps
  • Pistol gas tube
  • Charging handle
  • Chrome-lined BCG

300 Blackout Build Kit Extras:

  • Buffer tube and spring
  • Shockwave pistol blade
  • Lower parts kit
  • 7075 80% forged lower receiver

No FFL Required

This complete .300 blackout build kit is the most effective way to finish your first .300 blackout AR-15 without any guesswork. The entire barrel and gas system are head-spaced and pre-installed, and everything ships to your door with no FFL required and no paperwork needed!

It is your responsibility to fully understand all applicable laws and regulations regarding purchase and ownership of uppers with a barrel length of less than 16″.

Please note: This AR-15 Build Kit requires that the builder completes the 80% lower receiver themselves, but that’s the fun part (and the only way to build your own AR-15 without the need of an FFL transfer or serialization).

No FFL required Made in the USA Lifetime Warranty

300 Blackout AR 15 Rifle Kit (10.5″ Stainless Barrel & 10″ M-Lok Handguard) w/ 80% Lower

$700.00 $550.00 (You Save $150 )

$700.00 $550.00 (You Save $150 )
Save For Later
Save For Later

Free Shipping on all orders $325+!


Sign-up for exclusive discounts, new product releases and updates from

100% Satisfaction

Customer Service is our passion and we are here to answer any questions you have.

Shop With PRIDE

Shop With Confidence

Secure Payment

Left Menu IconMENU
Right Menu Icon