The Bluegrass AR-15 Upper Build Kit is an upper assembly package built around a 16 inch 4150 CrMoV barrel with a Nitride finish, medium profile, and a 1:16 twist rate for .350 Legend. The upper receiver is machined from 7075-T6 aluminum with an anodized finish and M4 feed ramps, paired with a 15 inch MLOK handguard made from 6061-T6 aluminum. This kit covers the upper receiver, barrel, and handguard as the core front end components of an AR-15 rifle build. BCG and charging handle are not included.
This kit uses a 16 inch barrel made from 4150 CrMoV with a Nitride finish and a medium profile. The 1:16 twist rate is suited to a wide range of .350 Legend bullet weights, and the 5/8x24 thread pitch matches the included GI birdcage flash hider. A carbine length stainless steel gas tube runs to a micro low-profile gas block sized for a 0.750 gas block diameter. The barrel and gas components make up the front end of this upper build kit.
The upper receiver is machined from 7075-T6 aluminum and finished with a durable anodized coating. It features M4 feed ramps for reliable feeding geometry. A 15 inch MLOK handguard made from 6061-T6 aluminum surrounds the barrel without contacting it, completing the exterior forend included in this kit.
Follow safe handling and manufacturer instructions.
Ensure compliance with all applicable federal, state, and local laws.
BCG and charging handle are not included.
Component specifications are subject to the details provided in this listing.
Platform: AR-15
Caliber: .350 Legend
Color: Black
Barrel Length: 16-inch
Barrel Material: 4150 CrMoV
Barrel Finish: Nitride
Barrel Profile: Medium
Barrel Twist Rate: 1:16
Barrel Thread Pitch: 5/8x24
Upper Receiver Material: 7075-T6 Aluminum
Upper Receiver Finish: Anodized
Feed Ramp Style: M4
Gas Tube: Carbine Length Stainless Steel Gas Tube AR15
Gas Block Size: 0.750
Gas Block Style: Micro Low-Profile
Handguard Length: 15-inch
Handguard Material: 6061-T6 Aluminum
Handguard Style: M-Lok
Muzzle Device: AR-15/AR-10 .308 5/8x24 TPI GI Birdcage Flash Hider for .308 7.62x39 .300 Blackout
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