DIY: How to Pin & Weld a Muzzle Brake

In their perfect, all-knowing wisdom, the United States Congress in 1934 limited the legal length of a rifle barrel to no shorter than 16 inches. For barrels under 16 inches, the National Firearms Act requires gun owners to apply for a special license and render unto Uncle Sam a $200 tax stamp.

This project isn’t difficult as long as you have access to a welding machine and someone who knows how to use it.

But the Act includes a caveat. Barrels are measured from the breech face to “the furthermost end of the barrel or permanently attached muzzle device.” A barrel can be 14.5 inches long, for example, provided a 1.5-inch muzzle device is also permanently affixed.

According to the National Firearms Handbook, “Permanent methods of attachment include full-fusion gas or electric steel-seam welding, high-temperature (1100°F) silver soldering, or blind pinning with the pin head welded over.”

The Daniel Defense Extended Muzzle Climb Mitigator is a great option for this project. They offer the brake in 5.56 and .30 caliber.

In my never-ending quest to avoid the NFA licensing process, I opted in my most recent AR build to purchase a 14.5 inch Ballistic Advantage barrel and pin/weld a 2 inch Daniel Defense muzzle brake to the end of it.

It may not be the most practical option (I only saved about 2 inches of overall length), but I enjoyed the project and I think the barrel/brake looks great with my 15 inch Rainer Arms rail.

Step 1: Choose your Muzzle Device

Keep two things in mind when choosing your muzzle device: barrel length and rail length. If you’re using a muzzle brake, pick one that both meets or exceeds the 16 inch mark and one that will clear your rail.

As the pin/weld option is gaining popularity, many gun parts manufacturers offer brakes designed specifically for this purpose. Daniel Defense offers an extended version of their Muzzle Climb Mitigator to ensure the brake holes will clear a 15 inch rail. I’ve also seen muzzle devices with a pre-drilled hole (more on that below).

You can also use other muzzle devices (flash suppressors, flash cans, etc.) that direct the blast forward instead of upwards. In that case, your only concern will be to meet the 16 inch barrel + brake requirement.

Step 2: Drill the Hole

Be patient on this step. It takes time.

For me, drilling the hole in the brake was the most time-consuming part of the process. This is a poor man’s how-to guide (see title), which means I didn’t have the fancy tools that are probably necessary for this job. But that’s never stopped me before, and with the combination of a Dremel tool and a power drill I made it through eventually.

I opted to drill the hole before installing the muzzle device. There’s a risk to this method, of course, and I nearly wasn’t able to thread the brake onto the barrel. But it was much easier to work with the brake pre-install, and I knew exactly when I’d drilled far enough.

I chose the bit size based on the pin I planned to use. It doesn’t have to match perfectly. It just needs to be large enough for the pin to fit and small enough to keep the pin upright.

Done. Not the prettiest job in the world, but a little touch up paint will go a long way.

Step 3: Measure and Cut the Pin

A Dremel bit will cut through easily enough. I used a 3/32” steel punch.

I used the end of a steel punch for my pin. I dropped the punch into the hole, marked the appropriate length, and cut it with a Dremel tool.

Step 4: Install the Pin

First, install your muzzle device like you normally would.

The pin needs to be seated into the barrel threads so that the brake cannot be turned once the weld covers the pin. For that, I returned to my drill/Dremel combination and cut a small indent into the threads. Obviously, you don’t want to get carried away at this point—drilling all the way through would likely ruin the barrel.

Once you have a small hole, simply tap the pin into it until the pin is secure. It’s also helpful to round one side of the pin so it seats more firmly in the indent in the threads.

Step 5: Weld the Pin in Place

I don’t know how to weld, but I know someone who does. He was kind enough to help me out, and he had it done in a matter of seconds.

I wanted to file down the bubble and paint over it, but I decided against it. The weld should be obvious, just in case the gun is ever inspected by authorities.

This is how we set up the weld. You may have to scrape a bit of paint off the muzzle device to get a good connection.

The weld didn’t take any time at all.

Conclusion

The white specs brush off easily. After that, you can paint the bubble to match your brake and barrel.

I found pinning and welding my muzzle device to my barrel to be a relatively simple project. Drilling the pin hole was time-consuming but not difficult. And once I cut a correctly sized pin, the weld was a piece of cake.

If you develop hives at the thought of marring your muzzle device, this project probably isn’t for you. Also, if you aren’t 100% sure about your barrel/brake configuration, pinning and welding isn’t the way to go. It is possible to remove the muzzle device, but you might not be able to salvage the threads on your barrel. “Permanently affixed” means exactly that.

That being said, a little touch-up paint can make the weld almost invisible, and I’m confident that my muzzle device won’t be too disruptive to my fellow shooters at the range.

If you used a different method, let us know about it in the comments!