Brownells Brn-15 5.56Mm 16'' Bbl .750'' Gas Block Upper Receiver

The Brownells BRN-15 5.56mm 16-inch upper receiver is a complete, US-manufactured upper assembly built for shooters who want a proven platform for their next AR build. This forged mil-spec upper comes with a nitride-finished 4150 CMV barrel, integrated handguard, and all the controls you need—minus only the bolt carrier group and charging handle, letting you select those components to match your shooting style and budget.

Built with attention to real-world use, the BRN-15 combines a medium-profile government-contour barrel with a low-profile .750-inch gas block and a full-length M-LOK handguard that extends past the block to give you maximum rail space for optics, lights, and accessories. The handguard features anti-rotation tabs that lock it to the upper receiver, eliminating any twist relative to your optics or iron sights, and dual screws torqued through the barrel nut keep it rock-solid in place. Cooling vents toward the rear of the handguard help both barrel and rail shed heat during sustained fire or a long practice session.

The upper itself is forged 7075-T6 aluminum with hardcoat anodize, M4 feed ramps in both the upper and barrel extension, a mil-spec ejection port cover, and a knurled forward-assist pin for easy replacement down the road. The barrel is stress-relieved, chamber-marked "5.56 NATO 1:7 4150CMV SR," and comes threaded 1/2-28 with an A2 flash hider already installed. Every part is made in the USA, and the 16-inch length strikes a balance between handling and velocity for hunting, 3-gun, and general-purpose shooting.

This is an upper receiver only—you'll need to source a bolt carrier group and charging handle separately to complete your build. The muzzle device is secured with a lock nut; loosen it with a wrench before removing or swapping the flash hider.

Key Features

• Forged mil-spec upper receiver with hardcoat anodize and M4 feed ramps
• 16-inch medium-profile 4150 CMV barrel, stress-relieved and nitride-finished
• 1:7 twist rate, 1/2-28 threaded with A2 flash hider installed
• .750-inch low-profile gas block with secure dimple and rear screw
• Full-length M-LOK handguard with anti-rotation tabs to prevent cant
• Dual-screw barrel nut clamp with cooling vents for rapid heat dissipation
• Knurled forward-assist pin for simple future swaps
• 100% US-made components

Specifications

Frequently Asked Questions

What bolt carrier group and charging handle do I need?

The BRN-15 upper is a standard mil-spec AR-15 upper receiver, so it will accept any mil-spec bolt carrier group and charging handle. Brownells sells both as separate components, and you can choose based on your budget and preference for weight, coating, and carrier profile.

Is this upper receiver a complete upper assembly or does it need more work?

It comes complete with the barrel, gas block, handguard, muzzle device, and all receiver controls. You only need to add a bolt carrier group and charging handle to have a functioning upper that you can pair with a lower receiver.

Can I use this upper on my existing lower receiver?

Yes, the BRN-15 upper is a standard forged mil-spec upper that will fit any mil-spec AR-15 lower receiver.

Is the 16-inch barrel good for hunting?

The 16-inch length is a versatile choice. It offers a balance between velocity and handling, making it suitable for hunting at moderate ranges and for general-purpose shooting, including competition and training.