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JG15 300 Blackout Complete Upper Assembly – 6″




Caliber: 300 Blackout
Barrel Length: 6″
Gas Seat: 0.750″
Gas Placement: Pistol-Length
Gas Block: Low profile JG Gas block
Twist Rate: 1:7
Barrel Material: CMV Alloy
Barrel Finish: QPQ Nitride
M4 Feed Ramps: Yes
Muzzle Thread Pattern: 5/8-24
Muzzle Device: JG 3-Stage Muzzle Brake
Upper Receiver Finish: Class III Type 2 Hard Coat Anodize
Charging Handle: JG Ambidextrous Charging Handle
Handguard: JG 7” M-LOK Handguard
Bolt Carrier Group: JG 300 Blk/5.56 NATO/.223 Rem Nitride BCG
Dust Cover: UTG Plastic Dust Cover


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When 300 Blackout hit the market, it took the AR-15 to a whole new level in the shooting arena. If you’re not already a fan of this cartridge, take it to the range, afterwards you will be. If you’re in the market for a complete upper assembly that performs in CQC/CQB and also doubles as an effective mid-range weapon, the Jacob Grey 6” 300 Blackout Complete Upper Assembly is just what you’re looking for.


The Jacob Grey barrel is designed with a thicker wall to better handle excess heat while minimizing barrel whip. The increased strength, hardness, and high-temperature stability of 4150 Chrome Moly Vanadium barrels are better suited for full-auto and rapid fire. Our complete uppers comes with a JG 7” M-LOK handguard giving you plenty of space for all the accessories you could want. The JG 3-Stage Muzzle Brake helps mitigate the recoil impulse and felt recoil.


While the 300 Blackout round is common, the ammunition used greatly affects the performance of your Jacob Grey Upper Receiver. We test our upper receivers using 145gr subsonic ammunition, this may not be the round you prefer to shoot. Buffer weight and spring coil tension greatly affects your firearms performance. You may need to adjust buffer weight accordingly to suit your choice of round. H2 and H3 Buffers are commonly used with the 300 Blackout caliber. If unsure about your firearms performance seek help from a qualified gunsmith.


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