Proper way to pin a flash hider to a barrel?

AR/M4 AR Technical Discussion
1

I’m curious here, I have a 14.5 inch M4 barrel, this upper will be my M203 host, I need to permantly attach my flash hider to get it over 16". I’m going to install a Blackout hider so I can use my M4 2000 on it, it gives me the necessary length I need, but I’m not exactly sure how to do it to BATF standards. My plan is to drill the hider out, than a little into the barrel, I then want to tap the hider out, and use a set screw tightened into it. I then plan on using solder to fill the hole flush. Is this accepteable? This way if my hider were ever to be removed I could (easier than the pin method), or should I just drill it and install a pin, and then solder that flush?
Thanks

2

Basically what I did with a 14.5 is what u describe except I used a set screw that was to long and cut it/surface ground it flush with the hider. This removed any way of removing it.

3

Welded over Blind pin or silver solder are the two acceptable ways. But there’s no way to determine that anyway. If someone finishes over a perm job, you can’t tell how it’s been done.

Fucking stupid law.

4

Agreed! Sooooo, I could use jb weld sanded down and refinished and then if I ever had to remove it, I could? I do this on my Sea Doos, we fill the allen holes with cotton, than jb weld the hole over so the bottom is smooth, but if you ever need to pull the intake grat or ride plate, you can, the coton allows you to get a allen wrench back in the bolt if ever needed.

5

That obviously wouldn’t be a legal perm in the BATF’s eyes… :wink:

6

I tried silver solder but just couldn’t get enough heat into the barrel. I could get the BC1.5 glowing red hot enough to melt the solder but it just wouldn’t wick into the threads.

I ended up using a blind pin and welded over the pin with my Mig. It was way easier than I though. I don’t have a Tig and thought I was going to need to take it to someone else.

7

I can’t spot weld in 1 or more places? Or run a short bead?

8

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.

http://www.atf.gov/files/publications/download/p/atf-p-5320-8/atf-p-5320-8.pdf