Fayetteville 16-inch .350 Legend 1:16 Complete Upper Build Kit

Fayetteville .350 Legend Upper

The Fayetteville .350 Legend upper delivers a complete, ready-to-mount solution for AR-15 builders looking to step into a modern intermediate cartridge. This upper combines a 16-inch 4150 CrMoV barrel with a 6061-T6 billet aluminum receiver, all finished to mil-spec standards. The 15-inch M-Lok handguard provides mounting flexibility, while the micro low-profile gas block keeps the profile clean. Everything you need is here except the lower receiver and stock or brace.

Key Features

• 16-inch 4150 CrMoV barrel with 1:16 twist, phosphate finish, government profile
• 6061-T6 billet aluminum upper receiver with Type III hard coat anodized finish
• 15-inch M-Lok handguard for modern accessory mounting
• Micro low-profile gas block with carbine length stainless steel gas tube
• Complete bolt carrier group in 9310 alloy steel with nitride finish
• Steel flash can muzzle device with 5/8x24 threads, 9mm and .350 compatible
• AR-15 M4 charging handle, mil-spec quality
• Ejection port door assembly included

Perfect For

• Builders seeking an intermediate cartridge platform with modern ergonomics
• Shooters wanting a complete upper that requires only a lower receiver
• Those interested in .350 Legend ballistics without a full custom build
• Hunters and sport shooters building a dedicated .350 platform

.350 Legend Platform Performance

The .350 Legend sits between 5.56 NATO and .308 Winchester in terms of power and recoil. This upper uses a 1:16 barrel twist optimized for .350 ammunition, ensuring reliable cycling and accuracy across the standard ammunition range. The carbine length gas system keeps the action running smoothly while maintaining a compact overall profile. The 16-inch barrel length balances velocity retention with practical handling.

Billet Aluminum Construction and Precision

The 6061-T6 billet aluminum receiver is machined to tight tolerances and finished with Type III hard coat anodizing for durability and corrosion resistance. This material choice provides strength without unnecessary weight. The micro low-profile gas block keeps the upper receiver profile minimal while maintaining reliable gas management. All internal surfaces are finished to spec for long-term reliability.

M-Lok Handguard Integration

The 15-inch M-Lok handguard offers modern mounting versatility for optics, lights, and vertical grips. M-Lok slots are spaced along the top and sides, giving you flexibility in accessory placement. The handguard remains slim and lightweight, preserving the overall balance of the rifle. This setup supports both tactical and hunting configurations.

Flash Can and Muzzle Device Compatibility

The steel flash can design muzzle device reduces visible muzzle flash while maintaining a clean aesthetic. The 5/8x24 threads are standard for .350 Legend and compatible with common suppressors and muzzle devices. The black oxide coating resists corrosion and blends with the rest of the upper. This device is compatible with 9mm platforms as well, offering flexibility if you build multiple uppers.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. BCG and charging handle are not included. Lower receiver not included.