AT3™ Assembled Pistol Upper for AR-15 – 8.5″ 300 BLK Barrel with 7″ Free Float Quad Rail
Built to Order – Ships Within 3 Business Days
This assembled upper delivers an ultra-compact, hard-hitting platform for AR pistol builds with the proven reliability of quad rail accessory mounting. This is the foundation for shooters building a suppressor host, backpack gun, or the most compact defensive setup where you need maximum stopping power in the smallest package possible. The 8.5-inch barrel is purpose-built for 300 BLK—whether you’re running supersonic loads for hunting and home defense or subsonic rounds with a suppressor for quiet work. The 7-inch Pro Quad Rail gives you four sides of Picatinny rail for rock-solid mounting of lights, lasers, and foregrips without worrying about adapter compatibility.
The KAK OE-SPEC 8.5-inch barrel in 300 BLK pairs with a pistol-length gas system for reliable cycling with both supersonic and subsonic ammunition. The 7-inch Pro Quad Rail provides secure accessory mounting on all four sides while keeping the overall profile compact. The quad rail is lightened down all four sides for weight reduction while remaining solid enough to handle heavy use. Five integrated QD sockets give you multiple sling mounting options for any configuration.
Built on AT3’s slick side billet upper receiver with a low-profile .750 steel gas block and stainless gas tube, this setup is ready to run once you add your choice of bolt carrier group and charging handle. The AT3 birdcage flash hider effectively reduces muzzle flash and gives the muzzle a clean, finished look.
Note: Does not include bolt carrier group or charging handle. The upper is shipped fully assembled.
Features
- 8.5-inch barrel with pistol-length gas system for reliable cycling with supersonic and subsonic loads
- 7-inch Pro Quad Rail with four sides of Picatinny rail for secure accessory mounting
- Lightened rail design reduces weight while maintaining strength
- Five integrated QD sockets for multiple sling configurations
- Slick side billet upper receiver for clean lines
- Low-profile .750 steel gas block and stainless steel gas tube
- Birdcage flash hider reduces muzzle flash
- Available in Black, Flat Dark Earth, and OD Green
Specifications
- Brand: AT3 Tactical
- Model: Assembled Pistol Upper for AR-15 – .300BLK – 8.5″ Barrel – 7″ Free Float Quadrail – No BCG/CH
- MPN: FFQR-P-85-7-BLK-300
- Caliber: 300 BLK
- Barrel Length: 8.5 inches
- Gas System: Pistol-length
- Handguard Length: 7 inches
- Handguard Type: Free-float quad rail
- Handguard Material: 6061-T6 Aluminum
- Handguard Weight: 9 ounces
- Inside Diameter: 1.35 inches
- Upper Receiver: Slick side billet
- Gas Block: .750 low-profile steel
- Muzzle Device: Birdcage flash hider (5/8×24 thread)
- Color Options:
- Black
- Flat Dark Earth – H-267 Cerakote Magpul® Flat Dark Earth
- OD Green – H-232 Cerakote Magpul® OD Green
What’s Included – Installed
- 1x Assembled Upper Receiver
- 1x 7″ AT3 Pro Quad Rail Handguard
- 1x 8.5″ KAK OE-SPEC 300 BLK Barrel
- 1x AT3 Birdcage Flash Hider & Crush Washer
- 1x Pistol-Length Gas Tube
- 1x Low-Profile Gas Block
Products available on this page:
- AT3™ Assembled Pistol Upper for AR-15 - .300BLK - 8.5" Barrel - 7" Free Float Quadrail - No BCG/CH - 3 Colors - Black - Color: Black | SKU: FFQR-P-85-7-BLK-300
- AT3™ Assembled Pistol Upper for AR-15 - .300BLK - 8.5" Barrel - 7" Free Float Quadrail - No BCG/CH - 3 Colors - Flat Dark Earth - Color: Flat Dark Earth | SKU: FFQR-P-85-7-FDE-300
- AT3™ Assembled Pistol Upper for AR-15 - .300BLK - 8.5" Barrel - 7" Free Float Quadrail - No BCG/CH - 3 Colors - OD Green - Color: OD Green | SKU: FFQR-P-85-7-ODG-300
