Brownells Brn-4 Hk416 Type Gas Block, 10.4'' Barrels

The Brownells BRN-4 HK416-type gas block is purpose-built for 10.4" HK416 barrels, delivering the durability and precision needed in modern rifle builds. Unlike standard AR-pattern gas blocks, this billet-steel unit is engineered specifically for 416-platform barrels and cannot be substituted with conventional AR15 or M16 gas blocks—compatibility matters, and Brownells got it right for your platform.

Machined from 4140/42 steel and hardened with a black nitride finish, this gas block is built to survive hard use. The interior chamber that accepts the piston head is carefully honed and finished to eliminate machine marks, ensuring smooth cycling and reliable performance over thousands of rounds. The alignment tab at the rear seats against the barrel to guarantee consistent gas port alignment and proper gas flow every time you assemble or reassemble your rifle.

Installation requires HK416-type coil pins—standard AR hardware won't work here, so plan accordingly when you order. The gas port sizing on HK416 barrels differs from civilian AR barrels, which is why a dedicated gas block matters; this unit is matched to that specification. Whether you're building a precision rifle, upgrading an existing 416 platform, or replacing a worn component, the BRN-4 delivers the fit and finish Brownells is known for.

Key Features

• Billet 4140/42 steel construction for durability under extreme conditions
• Black nitride finish provides hardness and corrosion resistance
• Precisely honed piston chamber eliminates machine marks and ensures smooth operation
• Alignment tab ensures proper barrel seating and consistent gas flow
• Specifically designed for 10.4" HK416-type barrels
• Requires HK416-type coil pins for installation

Specifications

Frequently Asked Questions

Can I use this gas block on a standard AR15 barrel?

No. The BRN-4 is designed exclusively for HK416-type barrels and gas block journals. Standard AR15 and M16 barrels have different gas port sizing and journal specifications, so this block will not fit or function properly on those platforms.

What fasteners do I need to install this gas block?

You'll need HK416-type coil pins for installation. Standard AR-pattern hardware is not compatible.

Does this work with 14.5" or 16" barrels?

No. This is the 10.4" model. Brownells offers separate gas block models for 14.5" and 16" HK416 barrels; gas ports differ between barrel lengths, so you must match the block to your barrel size.

What's included in the box?

The gas block itself is included. Coil pins and any other hardware must be purchased separately.