Brownells Brn-4 Stripped Barrel,16.5'' Heavy, 1-7, 1/2''-28, Blk Nitride

Building or upgrading a BRN-4 upper receiver? The Brownells BRN-4 Stripped Barrel in 16.5" Heavy profile is engineered specifically for HK 416–compatible systems, giving you a purpose-built barrel that actually fits the platform without hunting for oddball compatibility solutions. Machined by Faxon and finished in durable black nitride, this barrel delivers the rigid, minimal-flex performance of classic HK 416 heavy profiles while accepting standard 5.56 NATO and .223 Remington ammunition. It's the kind of no-compromise part that turns a parts-bin build into a cohesive rifle.

The 1-7 twist rate and ½"-28 muzzle threads give you flexibility for your preferred ammunition and muzzle device, while the deep black nitride—applied inside and out—resists corrosion and cleans easily after range sessions or field use. The extended barrel extension on the BRN-4 design ensures a solid fit to your upper receiver and simplifies installation. Pair this stripped barrel with the matching BRN-4 bolt carrier group, gas block (specify the length-appropriate model), and barrel nut for a complete upper assembly, or integrate it into an existing BRN-4 build.

This is a stripped barrel—you'll need the proper barrel nut, gas block, and gas block coil pins to complete your assembly. Torque the barrel nut to 50–80 ft/lbs for reliable function. If you're running a BRN-4 platform and tired of compromise parts, this barrel closes the gap between budget builds and precision performance.

Key Features

• HK 416–compatible design, machined by Faxon for precision fit
• 16.5" heavy profile delivers rigidity and minimal flex
• 1-7 twist rate for 5.56 NATO and .223 Remington
• ½"-28 muzzle threads for standard suppressors and flash hiders
• Deep black nitride finish inside and out for durability and corrosion resistance
• Extended barrel extension for robust upper receiver fit
• Button-rifled construction

Specifications

Frequently Asked Questions

What components do I need to complete this barrel assembly?

This is a stripped barrel—you'll need a BRN-4 barrel nut (Brownells part 430-100-141), the correct BRN-4 gas block for your barrel length, gas block coil pins (430-103-127), and the piston rod assembly (078-000-644). The gas blocks are available separately based on length; confirm which model matches your 16.5" barrel.

Is this barrel compatible with standard AR-15 upper receivers?

No. This barrel is designed specifically for HK 416–compatible upper receivers and the BRN-4 platform. The extended barrel extension is engineered for that system. Verify your upper receiver is BRN-4 compatible before purchasing.

What ammunition does this barrel shoot?

This barrel is chambered in 5.56 NATO and will also function with .223 Remington ammunition. The 1-7 twist is suitable for a wide range of commercially available loads in both cartridges.

Can I use a suppressor with the ½"-28 threads?

Yes. The ½"-28 muzzle threads are standard and compatible with most commercial suppressors, flash hiders, and muzzle brakes designed for that thread pitch. Install your chosen muzzle device and ensure all connections are tight and secure.