AT3™ Assembled Forged Upper for AR-15 – 16″ 5.56 NATO Barrel with 9″ Free Float Quad Rail – Rosco Bloodline Barrel
Built to Order – Ships Within 3 Business Days
This assembled upper delivers a full-length, reliable platform for AR-15 builds with the proven reliability of quad rail accessory mounting and the properly-gassed performance of a Rosco Bloodline barrel. This is the foundation for shooters building a versatile home defense rifle, duty gun, suppressor host, or all-purpose range blaster where you need the full velocity and reliability of 5.56 NATO without the violent over-gassing of standard M4 barrels. The 9-inch Pro Quad Rail gives you four sides of Picatinny rail for rock-solid mounting of lights, lasers, foregrips, and any other accessories you need without worrying about adapter compatibility.
The 16-inch Rosco Bloodline barrel solves the over-gassed carbine problem with properly engineered gas port sizing that prevents excessive bolt speed and premature wear. Built from 4150 CMV steel with nitride finish, this barrel delivers reliable function without the violent cycling of standard M4 profiles—reducing premature wear from excessive gas while working exceptionally well with suppressors. The 1:7 twist rate stabilizes heavy projectiles, and the carbine-length gas system provides reliable cycling. The 9-inch Pro Quad Rail provides secure accessory mounting on all four sides, is lightened down all four sides for weight reduction while remaining solid enough to handle heavy use, and features five integrated QD sockets for multiple sling mounting options.
Built on AT3’s forged upper receiver with forward assist and dust cover installed, this setup pairs a low-profile .750 steel gas block and stainless gas tube for reliable function. The Mil-Spec A2 flash hider effectively reduces muzzle flash and gives the muzzle a clean, finished look. Engineered with military and consumer input for balanced performance.
Note: Does not include bolt carrier group or charging handle. The upper is shipped fully assembled.
Features
- 16-inch Rosco Bloodline barrel with properly sized gas port prevents over-gassing
- 4150 CMV steel with nitride finish for durability
- 1:7 twist rate stabilizes heavy projectiles
- Carbine-length gas system with balanced cycling
- Optimized for suppressor use
- 9-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
- Forged upper receiver with forward assist and dust cover installed
- Low-profile .750 steel gas block and stainless steel gas tube
- Mil-Spec A2 flash hider reduces muzzle flash
- Available in Black, Flat Dark Earth, and OD Green
Specifications
- Brand: AT3 Tactical
- Model: Assembled Forged Upper for AR-15 – 5.56 NATO – 16″ Barrel – 9″ Free Float Quadrail – No BCG/CH
- MPN: FFQR-FOR-R-16-9
- Caliber: 5.56 NATO
- Barrel Length: 16 inches
- Barrel Profile: M4
- Barrel Material: 4150 CMV steel
- Barrel Finish: Nitride
- Barrel Twist: 1:7
- Gas System: Carbine-length
- Handguard Length: 9 inches
- Handguard Type: Free-float quad rail
- Handguard Material: 6061-T6 Aluminum
- Handguard Weight: 12 ounces
- Inside Diameter: 1.35 inches
- Upper Receiver: Forged with forward assist and dust cover
- Gas Block: .750 low-profile steel
- Muzzle Device: A2 Mil-Spec flash hider (1/2×28 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 9″ AT3 Pro Quad Rail Handguard
- 1x 16″ Rosco Bloodline M4 Profile Barrel
- 1x A2 Mil-Spec Flash Hider
- 1x 1/2″ Crush Washer
- 1x Carbine-Length Gas Tube
- 1x Low-Profile Gas Block
- 1x Forward Assist
- 1x Dust Cover
Products available on this page:
- AT3™ Assembled Forged Upper for AR-15 - 5.56 NATO - 16" Barrel - 9" Free Float Quadrail - No BCG/CH - 3 Colors - Black - Color: Black | SKU: FFQR-FOR-R-16-9-BLK
- AT3™ Assembled Forged Upper for AR-15 - 5.56 NATO - 16" Barrel - 9" Free Float Quadrail - No BCG/CH - 3 Colors - Flat Dark Earth - Color: Flat Dark Earth | SKU: FFQR-FOR-R-16-9-FDE
- AT3™ Assembled Forged Upper for AR-15 - 5.56 NATO - 16" Barrel - 9" Free Float Quadrail - No BCG/CH - 3 Colors - OD Green - Color: OD Green | SKU: FFQR-FOR-R-16-9-ODG








