Brownells Brn-4 5.56X45 Nato 16'' Heavy Chrome Lined Barrel, Phosphate

The Brownells BRN-4 5.56x45 NATO 16" heavy barrel is a professional-grade replacement barrel built for shooters who want authentic HK 416 upper receiver compatibility with proven Faxon machining. This 16-inch heavy-profile barrel delivers the rigid, minimal-flex construction found on earlier HK 416 models—ideal for precision rifle builds, range work, or duty applications where barrel stiffness directly impacts accuracy. The BRN-4 lineup fills a historically hard-to-source gap in the aftermarket, giving you a drop-in solution that works seamlessly with BRN-4 bolt carrier groups, gas blocks, and upper receivers.

Built with button rifling and a 1:7 twist rate, this barrel handles the full spectrum of 5.56x45 NATO ammunition as well as .223 Remington cartridges—giving you flexibility at the ammo counter without guessing on gas system compatibility. The 1/2"-28 muzzle threads accept standard suppressors and muzzle devices, and the extended barrel extension locks into your receiver with a solid, repeatable fit using the BRN-4 barrel nut. A deep phosphate finish provides a hard, durable exterior and interior that's straightforward to clean and maintain in the field.

Installation is straightforward for anyone comfortable working on their rifle. The 16-inch length suits full-size AR platforms and benefits from standardized piston rod assembly dimensions across the BRN-4 barrel range—simply pair it with the correct BRN-4 gas block for your barrel length. Torque the barrel nut to 50–80 ft/lbs and you're set. Whether you're upgrading an existing build or assembling a complete rifle, the BRN-4 heavy barrel gives you proven compatibility and no-compromise machining.

Key Features

• HK 416 upper receiver compatible—fits early-generation HK 416 components
• Heavy profile barrel—maximum rigidity and minimal flex for accuracy
• Button rifled, 1:7 twist—handles 5.56x45 NATO and .223 Remington
• 1/2"-28 muzzle threads—compatible with standard suppressors and muzzle devices
• Extended barrel extension—robust receiver fitment and simplified installation
• Phosphate finish—durable, hard-wearing, easy to clean
• 16-inch barrel length—ideal for full-size AR platforms

Specifications

Frequently Asked Questions

Will this barrel fit my HK 416 upper receiver?

Yes, the BRN-4 barrel is designed for early-generation HK 416 upper receivers and components. The extended barrel extension provides a robust matchup to the receiver, and installation is straightforward using the BRN-4 barrel nut.

What ammunition does this barrel shoot?

The barrel is chambered in 5.56x45 NATO and also fires .223 Remington cartridges, giving you broad ammunition compatibility at any gun counter.

What gas block and piston rod do I need?

All BRN-4 barrels use the same piston rod assembly. Select the correct BRN-4 gas block to match your barrel length, and include the gas block coil pins during final assembly. Be sure to torque the barrel nut to 50–80 ft/lbs for proper fit.

Can I install a suppressor on this barrel?

Yes. The barrel features 1/2"-28 muzzle threads, which are compatible with standard suppressors and muzzle devices of your choice.