If you take a sub-16" barrel and pin/weld a muzzle device per ATF guidelines, bringing the length to at least 16", but file/sand/expertly touch-up the weld so that it is not visible to the naked eye, how would an agent/LEO determine that you are within the law? How could you protect yourself against any legal issues?
Sorry if this has been addressed, but I searched and didn’t find it.
Thanks,
Pete
This may be a foolish question, but why?
Assuming you meant “why would you not just get a 16” barrel in the first place", well, the price was right. 
Im no welder, but I think you would have to be pretty skilled to completely mask a pin / weld after leaving the manufacturer. Why would you want it that finely finished in the first place? It seems it would only incite attention.
I’m no welder either, but I know several metal guys that could easily get the job done such that, with a coat of Krylon, you’d never see it.
As to your last question and comment, short of an answer to my original questions, I would definitely leave the weld visible so as not to incite any undue attention.
Thanks,
Pete
I’ve seen several perm jobs that were nearly invisible. I wouldn’t lose sleep over it. The worst case scenario is that the gun would be taken as evidence pending examination, which would verify your compliance.
If you’re wanting extra insulation, retain an invoice from the folks doing that work that specifies what was done.
The overwhelming majority of cops won’t even notice, and of those that will, few will care.
A tape measure.
Gotcha; I need to find a better gunsmith 
I am too distracted by your avatar to address your comment. 
It’s camouflaged, you can’t see it.
i purposely leave it visible. i live surrounded by super dumb highway patrol
want them to see it
want them to know if they f–k with the barrel and a pipe wrench, i will own their sorry ass. had 1 threaten to do it 1 time in a drunk check at midnight. her boss told her to let it go. she copped and attitude at the car my wife was driving cause i had surgery. had 2 sbr’s n the car. she went bat shit and started looking for trouble. she got 3 days off and a reprimand in the file.
its only a gun, nuttin’ fancy, who cares what it looks like.
safe then sorry
good luck
I’ve seen factory soldered perms that don’t look obviously permed at all. I think you’d have to do something to draw attention to yourself before the Feds would inspect this type of thing.
Who’s to say you don’t bore a phantom hole in a flash hider and put a fake weld spot on there so you dont’ have to actually damage your barrel???
Actually, you live surrounded by the hard working men and women of the Highway Patrol, honorably serving you. I’m certain they have at least basic cognitive ability sufficient for the task.
want them to know if they f–k with the barrel and a pipe wrench, i will own their sorry ass.
No, they will end up buying you a new one.
Let’s dial the bravado down a bit, okay?
Thank you, that was going to be my point. To the OP, your defense is that if they try to remove it that it does not come off.
If someone welded a phantom hole and LEO removed the device the welding of the phantom hole would not be a defense.
Your best defense is, if asked, to politely explain to them what has been done to permanently attach the device.
Ive never had anyone ask including LEO’s who were at the range, too. I don’t think you’d really draw any attention unless the barrel is obviously short. I don’t think anyone is going to be sticking a rod down the barrel on the spot to measure it, and tell them its welded but refinished should be enough.
If I’d refinished this one no one would have known. It was perfectly flush and rounded with the NT4 mount.
AFAIK, they would simply put it in a vise and attempt to turn it. If it resists getting twisted off, it is considered to be permanently attached. This does not come from personal knowledge, just what I was told by the smith that worked on mine.
Elmore does a bang up job on his pin & weld rifles…
http://www.specializedarmament.com/products/7_LE6921_Special_Edition-900-2.html
No doubt. The last Sabre I looked at I couldn’t find it and figured it had to be soldered.
Get an SBR and then you won’t have to worry about stupid things like this.
Yep. It’s $200 just one time and then no-BS.
Sometimes I just don’t see the logic in people who’ll blow $200 on dumb stuff but not on something like a tax stamp.