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

The Brownells BRN-4 stripped barrel in 16.5-inch medium profile is purpose-built for shooters assembling HK 416-compatible uppers who want a balance of handling speed and rigidity without excess weight. Machined by Faxon and finished in hard black nitride inside and out, this barrel delivers the durability you need for serious use—whether you're running drills at the range, building a duty rifle, or setting up a precision platform. The medium contour saves weight compared to the classic heavy profile while maintaining barrel stiffness where it matters, making your rifle noticeably handier without compromise.

Chambered in 5.56x45mm NATO with a 1-7 twist rifling, this barrel runs both standard NATO ammunition and .223 Remington rounds with equal reliability. The 1/2"-28 muzzle threads accept any industry-standard muzzle device—suppressors, flash hiders, brakes—giving you the flexibility to tailor the barrel to your mission. The extended barrel extension ensures a solid, robust fit with early-generation HK 416 upper receivers and simplifies installation when paired with the BRN-4 barrel nut (torque to 50–80 ft/lbs). All BRN-4 barrels use the same piston rod assembly, so you'll just need to match your gas block to the 16.5-inch length for proper function.

This is a stripped barrel—no gas block or gas tube included—so you're building it to spec. If you're finishing the upper, you'll need to source a compatible BRN-4 gas block and the gas block coil pins separately. The nitride finish resists corrosion and cleans easily, holding up to regular use and storage. Straightforward, no-nonsense engineering: a barrel that works.

Key Features

• 16.5-inch medium profile — lighter than heavy contour, maintains rigidity and handling
• 1-7 twist rifling — stabilizes a wide range of 5.56mm and .223 projectiles
• 5.56x45mm NATO chambering — runs both NATO-spec and .223 Remington ammunition
• 1/2"-28 muzzle threads — compatible with standard suppressors, flash hiders, and muzzle brakes
• Deep black nitride finish — hard, durable, corrosion-resistant, easy to clean
• Extended barrel extension — robust upper receiver fitment and simplified installation with BRN-4 barrel nut
• HK 416-compatible — fits early-generation HK 416 uppers and BRN-4 components

Specifications

Frequently Asked Questions

Will this barrel work with my HK 416 upper receiver?

Yes, this barrel is designed to fit early-generation HK 416 upper receivers and other HK 416-compatible components. The extended barrel extension provides a robust interface and straightforward installation. You'll install it using the BRN-4 barrel nut.

What gas block do I need for the 16.5-inch barrel?

You'll need a gas block matched to the 16.5-inch barrel length. All BRN-4 barrels use the same piston rod assembly, so the correct gas block is essential for proper function. Refer to the BRN-4 gas block options available for this length. You'll also need gas block coil pins for final assembly.

Can I use .223 Remington ammunition in this barrel?

Yes. The 5.56x45mm NATO chambering safely and reliably runs both 5.56 NATO and .223 Remington ammunition.

What muzzle devices are compatible?

The 1/2"-28 muzzle threads accept any standard muzzle device in that size—suppressors, flash hiders, compensators, and brakes. This gives you flexibility to tailor the barrel to your needs.