Pinned & Welded

[Bansh88]

I recently got my 14.5 LMT upper. I have my extended flash hider on the way.
Can someone show me what the pin and weld looks like? Is just a small tack weld sufficient? The hider I'm getting has the predrilled hole. What pin should I look for? Should I get a new crush washer?
Any info, pics or link would be appriciated.

[Rob454]

I would just solder it. to the barrel. you can use silver solder or plumbers solder and flux. It makes it so its easier to remove without visible damage to the gun like a weld.

[Bansh88]

That will still be legal?

[redcliff]

Silver solder is legal, not sure about "plumber's solder". What isn't legal is having a short barrel upper without a pistol lower in your posession. Keep that short barrelled upper at someone else's house until you get it permanently modified. Unlike California AW laws, constructive posession does apply to Federal SBR violations.

[Bansh88]

Good to know!
So does it also HAVE to be pinned to be legal or would just solder make it "permanently" attatched?

[joemama]

Silver solder is legal, not sure about "plumber's solder". What isn't legal is having a short barrel upper without a pistol lower in your posession. Keep that short barrelled upper at someone else's house until you get it permanently modified. Unlike California AW laws, constructive posession does apply to Federal SBR violations.

I thought its only constructive posession if you have a rifle lower. If all he has is the pistol upper and no lower would he be in constructive possesion?

[Tony.]

Best option is for a pin and weld. If you do go the solder route, 1200 degree solder in required

http://www.contenti.com/products/soldering/420-841.html

Since the flash hider is already drilled you could drill a blind pin into the barrel, then solder over top of it.

[ke6guj]

per ATF:

2.1.3 Rifle. A rifle is a firearm designed to be fired from the shoulder and designed to use the energy of
an explosive in a fixed cartridge to fire only a single projectile through a rifled barrel for each single pull
of the trigger.11 A rifle subject to the NFA has a barrel or barrels of less than 16 inches in length.


The ATF procedure for measuring barrel length is to measure from the closed bolt (or breech-face) to
the furthermost end of the barrel or permanently attached muzzle device. . Barrels are measured by inserting a dowel rod
into the barrel until the rod stops against the bolt or breech-face. The rod is then marked at the
furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and
measured.

[redcliff]

I thought its only constructive posession if you have a rifle lower. If all he has is the pistol upper and no lower would he be in constructive possesion?

No, he wouldn't. You need a rifle lower for constructive posession along with the short barrel upper. Sorry I didnt make that clear previously.

[Jonathan Doe]

I think spot weld is good also. It still is a permanent method. Silver solder need to make the part very hot, usually red hot, and I wonder of that will affect the domension of the barrel, such as bore diameter and so on.

[ar15barrels]

I think spot weld is good also. It still is a permanent method. Silver solder need to make the part very hot, usually red hot, and I wonder of that will affect the domension of the barrel, such as bore diameter and so on.

Don't think, be sure of it.
The ATF description posted above is the safest interpretation.
The "common hand tools" test also applies.
If you can remove the permanently installed muzzle device with common hand tools (wrench, hammer, pliers etc...) without damage to the barrel, it's NOT permanent.
Even 1200 degree silver solder fails the "common hand tools" test.

The issue with 1200 degree silver solder is that you change the heat treating of the barrel and totally screw up the finish.
This makes the whole barrel need to be blasted and parkerized.
Then you have to watch that you get all the park solution out afterwards of you end up with this...



The best method by-far is to pin and weld.



The weld is much smaller with no heat treat damage to the barrel and no need to re-finish, other than the small welded area over the pin.

Removing a pinned muzzle device creates siginificant damage to the barrel, rendering is unusable:

[Bansh88]

Great info guys. thanks.
Now with the pin. It just pushes up against the the threads? It doesn't need to be "into" the threads, does it? Is there a specific pin to use?

[ke6guj]

The hole that you drill for the pin needs to go into the threads, so that when the pin is inserted, the FH/MB can't turn, without destroying the barrel, like pictured above.

[ar15barrels]

Great info guys. thanks.
Now with the pin. It just pushes up against the the threads? It doesn't need to be "into" the threads, does it? Is there a specific pin to use?

I drill the hole below the root of the threads to ensure I am in a good strong meaty area.

[Bansh88]

I had a thought on this:

Let's say worst case scenario, an ATF agent suspects an illegal SBR (due to an unpermanent flas hider). They take it in to test it. Are they going to wreck it just to find out either way?
Like the old Witch test? If she drowns she's not a witch but she's still f-ing dead