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Complete Build Kit – 300 Blackout (10.5″ SS Barrel & 10″ M-Lok Handguard) AR 15

$700.00 $550.00 (You Save $150.00)

Complete Build Kit - 300 Blackout (10.5" SS Barrel & 10" M-Lok Handguard) AR 15
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Free Shipping on all orders $325+!

SKU: UA300PHB10.517(SS)-(10)MLOK_Budget_No-Lower


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!

Need a California-Compliant Build Kit? Follow These 4 Steps!

1. Choose “CA-Compliant Lower Parts Kit” in the Lower Parts Kit dropdown.

2. Choose the “No Lower Receiver” option for the 80% Lower Receiver dropdown.

3. Select/Click “Add to Build”.

4. Head here to purchase a California-compliant 80% lower receiver

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

Complete Build Kit – 300 Blackout (10.5″ SS Barrel & 10″ M-Lok Handguard) AR 15

$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+!


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