WMD UPPER ASSY 300BLK 16" BARREL

The WMD Guns 300 BLK upper assembly gives you a complete, ready-to-mount upper receiver built around the proven .300 Blackout cartridge. With a 16-inch barrel and quality in-house manufacturing, this is a solid foundation for a short-range, subsonic-capable AR-platform rifle. Whether you're building a dedicated 300 BLK for hunting, suppressed shooting, or just want a shorter, handy configuration, a complete upper assembly saves you the headache of sourcing and assembling individual parts.

WMD Guns manufactures many of their components in-house, which means tighter control over quality and finishing. The upper itself is forged 7075-T6 aluminum and finished with hardcoat black anodize—a durable, professional coating that resists wear on the bench and in the field. The charging handle, bolt carrier group (BCG), and handguard receive WMD's NiB-X plating, a nickel-boron hybrid finish that reduces friction, improves reliability, and makes cleaning easier. You also get a low-profile gas block, gas tube, ejection port cover, forward assist, and a muzzle brake—all the hardware needed to complete your build or convert an existing lower receiver.

Drop this upper onto any AR-15 lower (in accordance with all applicable laws), and you've got a .300 Blackout rifle. The 300 BLK cartridge is inherently subsonic-friendly, making it a natural choice for suppressed shooting or hunting scenarios where noise matters. The 16-inch barrel strikes a balance between velocity and portability, useful for intermediate ranges and tight spaces where a full-length rifle might be awkward.

Key Features

• Complete upper assembly—no additional receiver, barrel, or bolt required
• Chambered in .300 Blackout for subsonic and supers versatility
• 16-inch barrel for compact, handy profile
• Forged aluminum upper with hardcoat black anodize finish
• NiB-X coated charging handle, BCG, and handguard for reduced friction and easier maintenance
• Includes low-profile gas block, gas tube, muzzle brake, ejection port cover, and forward assist
• In-house manufactured and finished by WMD Guns

Specifications

Frequently Asked Questions

What lower receiver does this .300 BLK upper fit?

This is a standard AR-15 upper assembly and will mount to any AR-15 lower receiver. Ensure all assembly is compliant with federal, state, and local firearm laws.

Does this come ready to shoot, or do I need a lower receiver?

This is an upper assembly only. You'll need to source an AR-15 lower receiver separately and assemble the two together to have a complete, functional rifle.

Can I suppress a 300 BLK rifle built with this upper?

The .300 Blackout cartridge is well-suited to suppressed fire, and this upper will work with a suppressor mounted to the muzzle brake. Check all applicable local and federal regulations regarding suppressors in your area.

What's included with the upper assembly?

The assembly includes the upper receiver, barrel, bolt carrier group, charging handle, handguard, gas block, gas tube, muzzle brake, ejection port cover, and forward assist. You will need to source a lower receiver separately.