Guys,
Does anyone know of a thorough “How To” guide on properly permanently attaching flash hiders to AR barrels? I would like to get set-up to do this procedure myself, as most guys that I build uppers for at work want the shorter OAL of the 14.5" barrel+extended flash hider (Vortex, Phantom, etc.). I am also interest in exactly which type of tools, bits, pins, etc. are necessary to complete the job properly. Thanks in advance!
BATF considers a FH that is silver soldered permanent. You can also pin the FH and weld over the ends of the pin. You can use an 1/8" roll pin, drill rod, nail, ect.
BATF considers a FH that is silver soldered permanent. You can also pin the FH and weld over the ends of the pin. You can use a 1/8" roll pin, drill rod, nail, ect.
I pinned mine through the FH and barrel and back through the FH on the other side, under the bore. Then welded the holes on both sides. It aint comin off, unless I drill through the welds and the pin. I know nothing about a “how to guide”, I just did what it took and took my time.
I see that Smith offers the Vortex pre-drilled with pins included for permanent attachment. I am assuming that siver soldering would be the easier route to get set-up with. Anyone have any info on the best way to silver solder? (Tools, process, etc.)
What type of drill bit should be used to drill into the barrel for the pin? How deep to drill?
Im not familiar with the Vortex kit, but for what its worth just a high speed steel drill bit will work and you’ll probably need a propane torch for the solder maybe a little flux to help the solder bond. Just my $.02.
gotm4 would have some good advice for you Im sure.
PAGING gotm4!!!
Heres a pic of the pre-drilled Vortex:
I don’t perm. mount FH’ers myself. Of the two methods mentioned to me the set screw/pin method is best since nothing is heated…heat can damage the steel. My preferred method is pinned and welded over but I have had them silver soldered before. Heating for silver solder also ruins the finish.
For this work I’ve used ADCO, AR15Barrels.com, Don at Special Projects Unlimited, Kurt at KKF and LWRC…all do excellent work.
I drilled my FH/barrel at the same time after I got it torqued and timed properly. I had measured the thickness where I wanted to drill and tacked on 0.060" to arrive at a total bore depth of 0.250" on a track mill. I used a 1/8" end mill to punch a flat hole and went really slowly to keep from binding and clear chips out of the hole. The 0.060" was easily enough to get me through the threads but left plenty of safety margin for the bore of the barrel.
After that my buddy filed the area around the hole a little bit, dropped an appropriately sized SS pin in, and TIG’d it in two stages to avoid overheating/penetrating the barrel. Probably a total of 5-6 seconds of welding and he added a little stick to it to help fill the hole. I filed and cleaned the weld, but left enough to prove it had been pinned, then blued it with cold blue.
Can a pin be peened/staked in place?
If you took a small roll pin, tapped it in the hole, then peened in the hole, you could not remove such a pin without a drill. It would be ‘permanent’ but would the BATF see it that way?
Nope. Only Silver solder and Pin ‘n’ Weld method are BATF approved for
permanent brake installation.
KyAKGuy