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Questions & Answers
So does this fit AR10 lowers or AR15 lowers ?

Ar15 lowers only

by Kos, Verified Owner, February 16, 2025
What mag will fit with this upper? Manufacturer Answer

We recommend using Duramag SS

by Jacob Grey, Manufacturer, October 24, 2023
Customer Reviews
Expert Review
Suberb Quality and Function by Andrew, Gear Expert, October 31, 2022
I am a huge fan of the 7.62x39 caliber, but am not a fan of AK rifles. I've tried several times to build a 7.62x39 AR platform firearm, but have always had issues with feeding, cycling, etc. I had just chalked it up to the fact that 7.62x39 wasn't d...
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10/10 found this helpful
Helpful Positive Review Nice fit - Nice action by Spence N, Verified Owner, January 22, 2024
Mounted this upper on my Anderson lower and it fit nice and cycled smoothly. Shot several mags of steel ammo and it shot nice with no ftf's. Running the std 3 oz buffer and seems to be fine but I may play with buffer weights later after more rounds ...
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1/1 found this helpful
Most Recent Reviews Very well machined and smooth action by Ben, Verified Owner, October 19, 2025
Everythfrom the barrel to the handguard is very nicely machined and finished. The bcg cycles like a much higher end bcg that is smooth like higher end finishes. I also like the charging handle. It does weigh around 3lbs 15ozs but it is lightweight ...
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Most Recent Reviews Today Was A Good Day by Dr. Acupunk, Verified Owner, March 21, 2024
Nice out of the box, glad it was on sale. No real complaints
Read All 4 Reviews

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Product Info for Jacob Grey Firearms Ultralight 7.62x39mm Complete Upper Assembly

The Jacob Grey Ultralight Complete Upper Assembly was designed with the next generation AR-15 in mind. This AR-15 complete upper assembly is built around the 7075-T6 billet upper receiver specifically machined and cut in areas where excess material was unnecessary and areas that see excess use and wear, reinforced and strengthened to give a sleek, refined look, without losing the classic lines of the AR-15 platform. It comes standard with the JG designed free float 7-sided M-LOK hand-guard that is also lightweight and leaves plenty of room for customization or the addition of numerous accessories available for the AR-15 platform. The barrel is chambered in 7.62x39 with a 1:10 twist rate. The barrel is machined from 4150 chrome moly steel and parkerized finished for corrosion resistance and accuracy. Each barrel is individually head-spaced to the Carpenter 158 bolt. Combined with the 8620 steel carrier and black Nitride finish, this complete upper assembly is extremely reliable and smooth shooting.image

DISCLAIMER: Firearm specifications are subject to change at any time based on availability and supply chain shortage.

Specifications for Jacob Grey Firearms Ultralight 7.62x39mm Complete Upper Assembly:

Manufacturer: Jacob Grey Firearms
Caliber: 7.62x39mm
Barrel Profile: Heavy
Barrel Twist Rate: 1-10
Threads per Inch: 5/8x24
Handguard Type: Free-Float
Muzzle Device: Brake
Finish: Type III Class 2 Hardcoat Anodized
Color: Black
Fabric/Material: Aerospace Aluminum
Gas Block Journal Size-Diameter: .075 in
Handguard Style: Round Rail
Gun Rail: M-LOK
Gun Type: Rifle
Gun Make: AR Platform
Gun Model: AR-15
Weight: 7.7 oz
Condition: New
Barrel Material: Chrome Moly
Gas Block Journal Size-Length: 1.9 in
Bolt Carrier Group Included: MIL-SPEC
Magazine Included: No
Charging Handle Included: MIL-SPEC
Mount Type: M-LOK

Features of Jacob Grey Firearms Ultralight 7.62x39mm Complete Upper Assembly

  • Compatible with most aftermarket/OEM handguards featuring indexing tabs
  • Billet 7075-T6 aerospace aluminum
  • Jacob Grey lightweight design
  • M4 feed ramps
  • Machined T-marks
  • Laser engraved logo
  • MIL-A-8625F Type III Class 2 hardcoat anodized flat black finish
  • Compatible with MIL-SPEC AR upper receiver parts
  • JG ULTRALIGHT Handguard

Package Contents:

  • Jacob Grey Firearms Ultralight 7.62x39mm Complete Upper Assembly

Jacob Grey Firearms Ultralight 7.62x39mm Complete Upper Assembly Orderable Models

List of Orderable Models

Jacob Grey Firearms Ultralight Complete Upper Assembly, 7.62x39mm, 7.5in, Black, 7623975ULCUA , MPN: 7623975ULCUA , UPC: 850040696103 , Code: 4M6-URC-GJUN3-7623975ULCUA
Jacob Grey Firearms Ultralight Complete Upper Assembly, 7.62x39mm, 10.5in, Black, 76239105ULCUA , MPN: 76239105ULCUA , UPC: 850040696097 , Code: 4M6-URC-GJUN3-76239105ULCUA

Jacob Grey Firearms Ultralight 7.62x39mm Complete Upper Assembly Unavailable & Discontinued Models

List of Unorderable Models

DEMO, Jacob Grey Firearms Ultralight Complete Upper Assembly, 7.62x39mm, 16in, Black, 7623916ULCUA , MPN: 7623916ULCUA-DEMO , Code: 4M6-URC-GJUN3-7623916ULCUA-DEMO
Jacob Grey Firearms Ultralight Complete Upper Assembly, 7.62x39mm, 16in, Black, 7623916ULCUA , MPN: 7623916ULCUA , UPC: 850040696080 , Code: 4M6-URC-GJUN3-7623916ULCUA
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