.300 Blackout Complete AR-15 Upper Receivers

Complete .300 BLK uppers for your AR-15 make swapping out calibers simple. Re-use your 5.56 BCG and mags!

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AT3™ 16 Inch .300 BLK Complete AR-15 Upper - .300 AAC Blackout 16 Inch Ballistic Advantage Barrel - With Nickel Boron BCG and Mil-Spec CH

AT3™ .300 BLK 16″ Complete Assembled AR-15 Upper – With Nickel Boron BCG and Charging Handle
$572.99
Only
$487.04
Out of Stock
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AT3™ 10.5 Inch .300 Blackout Pistol Upper for AR-15 - With Nickel Boron BCG and Mil-Spec CH

AT3™ 10.5 Inch .300 Blackout Complete Assembled Pistol Upper for AR-15 – With Nickel Boron BCG and Mil-Spec CH
$536.97
Only
$456.42
Out of Stock
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AT3 Tactical 10.5 Inch 300 BLK Complete AR-15 Upper Assembly - No BCG or Charging Handle
(13)

AT3™ 10.5 Inch .300 Blackout Assembled Pistol Upper for AR-15 – No BCG/CH
8 Options
from $391.99
from $333.19
Out of Stock
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AT3™ FF-ML 16 Inch .300 BLK Complete Upper - .300 AAC Blackout 16 Inch Ballistic Advantage Barrel - 15" M-LOK Free Float Handguard
(7)

AT3™ 16 Inch .300 BLK Assembled AR-15 Upper – 16 Inch Ballistic Advantage Barrel – No BCG/CH
8 Options
from $413.99
from $351.89
Out of Stock
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AT3™ .300BLK 16″ Assembled Forged Upper – 2A Basics ASAL 15" Handguard – No BCG/Charging Handle

AT3™ .300BLK 16″ Assembled Forged Upper – 2A Basics ASAL 15″ Handguard – No BCG/Charging Handle
$384.99
Only
$327.24
Out of Stock
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Radical Firearms 16" .300 Blackout Complete Upper Receiver with M-LOK Handguard - AT3 Tactical

Radical Firearms 16″ .300 Blackout Complete Assembled AR-15 Upper Receiver with M-LOK Handguard
Only
$383.99
Out of Stock
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Aero Precision M4E1-T AR-15 Assembled Upper 300 BLK 8″ – No BCG/Charging Handle
2 Options
from $534.99
Out of Stock
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AT3™ Assembled Pistol Upper for AR-15 - .300BLK - 8.5" Barrel - 7" Free Float Quadrail - No BCG/CH - 3 Colors

AT3™ Assembled Pistol Upper for AR-15 – .300BLK – 8.5″ Barrel – 7″ Free Float Quadrail – No BCG/CH – 3 Colors
3 Options
from $366.99
from $311.94
Out of Stock
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STNGR 10.5 Inch 300BLK Complete Upper w/ 13.5 Inch HWKXL® Handguard, BCG & CH

STNGR 10.5 Inch 300BLK Complete Upper w/ 13.5 Inch HWKXL® Handguard, BCG & CH
3 Options
from $646.99
Out of Stock
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AT3™ Assembled Forged Pistol Upper for AR-15 - .300BLK - 8.5" Barrel - 7" Free Float Quadrail - No BCG/CH - 3 Colors

AT3™ Assembled Forged Pistol Upper for AR-15 – .300BLK – 8.5″ Barrel – 7″ Free Float Quadrail – No BCG/CH – 3 Colors
3 Options
from $389.99
from $331.49
Out of Stock
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STNGR 8.5 Inch 300BLK Complete Upper w/ 7 Inch VYPR® Handguard, BCG & CH - 3 Colors

STNGR 8.5 Inch 300BLK Complete Upper w/ 7 Inch VYPR® Handguard, BCG & CH – 3 Colors
3 Options
from $571.99
Out of Stock
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