From The Bench: BRN-4 M38 On the Range

Today

In this video, Caleb from Brownells revisits the BRN-4 M38 designated marksman rifle build—an HK416-inspired platform—at the Big Spring Shooting Complex. Joined by Steve, Caleb showcases key upgrades including a Badger Ordnance mount with Trijicon RMR, an MDT bipod, and a Dead Air Sierra 5 suppressor. Using Winchester 69-grain SMK ammo, they test the rifle’s performance from 100 to 500 yards, achieving consistent hits on steel targets. Viewers get a detailed look at the rifle’s practical precision capabilities, making this video a must-watch for those interested in DMR builds and mid- to long-range shooting performance.

What You Will Learn

Viewers will gain valuable insight into configuring a DMR-style rifle based on the HK416 platform, including component selection, optic setup, and suppressor performance. The video demonstrates how specific upgrades improve stability, recoil management, and accuracy at various ranges.

Benefit

Whether you're planning a similar build or refining your own setup, this test offers practical takeaways for optimizing gear and shooting technique to hit targets at 500 yards and beyond.

Introduction

Hey everyone, Caleb from Brownells here. In this video, I’m out at the Big Spring Shooting Complex with Steve to test out our newly updated BRN-4 M38 build—a designated marksman rifle (DMR) setup based on the HK416 platform. The M38 configuration is essentially modeled after the Marine Corps’ 416-based DMR. We’ve made some key upgrades since the initial build, and today we’re stretching it out to 500 yards to see how it performs.

Build Overview and Upgrades

If you caught the first video on this rifle, you’ll notice a few changes this time around. While the optic remains the same, I swapped the original mount for a Badger Ordnance mount with a Trijicon RMR piggybacked on top. That setup gives me both magnified and red dot aiming options in a compact footprint.

I also added an MDT bipod for added stability and slapped on a Dead Air Sierra 5 suppressor, which keeps things quiet and adds weight for recoil control. It’s a well-rounded configuration built for practical precision shooting.

Ammo Selection

For this test, we’re running Winchester Match 69-grain Sierra MatchKing (SMK) ammo. This is a heavy boat-tail hollow point round that performs really well at mid- to long-range. It’s consistent, clean-burning, and ideal for a gun like this.

Range Test: 100 to 500 Yards

We started at the 100-yard line to confirm everything was still zeroed. Spoiler alert: it was.

From there, I worked my way out, engaging steel targets at 200, 300, 400, and 500 yards. Everything performed really well with minor adjustments. The wind and elevation calls were solid, and the gun stayed right on track.

The 400-yard shot required a quick elevation tweak, and I landed a solid hit—what we jokingly called a “heart shot.” At 500 yards, I had to correct slightly to the right, as we didn’t have a perfectly dialed-in zero for that range, but the rifle consistently rang steel.

Steve Takes a Turn

After I’d run the BRN-4 through its paces, Steve stepped in to give it a try. His first shots on the 500-yard plate were just a bit off, but after a quick adjustment, he landed multiple hits. The suppressor definitely helped manage recoil, and the MDT bipod made it easier to stay stable behind the rifle.

It’s worth noting that the HK-style short-stroke piston system doesn’t seem to hinder precision one bit. This rifle easily holds its own out to 500 and would likely go even farther with a bit of fine-tuning.

Final Thoughts

If you’re building a DMR-style rifle and want something based on the HK416 platform, the Brownells BRN-4 is a fantastic place to start. With the right mount, glass, ammo, and support gear, this setup is fully capable of precision hits out to 500 yards and beyond.

As always, if you’ve got questions about this build, your own setup, or any gear mentioned here, drop them in the comments or give the Brownells Tech Line a call. We’re always happy to help.

Thanks for watching, and we’ll see you next time.

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