New Products: BRN-4 Complete Upper Receivers

In this video, Paul Levy from Brownells introduces the BRN-4 Complete Upper Receiver Assembly—a factory-built, piston-driven upper now available fully assembled. He walks through its key features, including multiple barrel lengths and profiles, compatibility with 416-style handguards, and ease of customization. Designed for builders who want flexibility without the hassle of piecing together a kit, the BRN-4 upper fits any standard AR-15 lower and offers a durable, accurate platform for your next build.

What You Will Learn

By watching this video, you'll learn about the features, specifications, and compatibility of the Brownells BRN-4 Complete Upper Receiver Assembly. You'll see the differences in barrel profiles and lengths, how to customize the upper with your own muzzle device and handguard, and how the BRN-4 integrates with standard AR-15 lowers. You'll also get a look at how easy it is to maintain the piston system and understand what makes this upper a unique option for modern rifle builds.

Benefit 

The benefit of watching this video is that it gives you a detailed overview of the Brownells BRN-4 Complete Upper Receiver Assembly, including its components, customization options, and compatibility with standard AR-15 lowers. It also shows you how to easily install and maintain the system, helping you make an informed decision if you're considering a piston-driven AR build or looking to upgrade your current setup.

What's Included

Each upper features:

• New Brownells production stripped receivers

• BRN4 barrels (multiple lengths and profiles)

• Gas block and op rod assembly

• BCG and charging handle

• Magpul dust cover

Barrel Options

Choose from a variety of configurations:

• 10.4" medium and heavy profile

• 14.5" medium and heavy profile (with length-specific gas blocks)

• 16" medium and heavy profile

All barrels are nitride-finished, 1:7 twist, and chambered in 5.56, with 1/2x28 threads for standard muzzle devices.

Ease of Assembly

• Compatible with standard 416 handguards

• No need to swap barrel nuts

• Anti-rotation indexing built into the upper

Maintenance & Compatibility

• Easy disassembly of the op rod and piston

• Standard AR-15 charging handle and bolt carrier group

• Fits any standard AR-15 lower (Aero Precision, BCM, etc.)

• Recommended: H1 or H2 buffers for optimal performance

Customization

Users can easily upgrade handguards, charging handles, and muzzle devices to build a setup tailored to their needs. Paul shows an example with a Geissele handguard to highlight flexibility.