Tell me if this has been covered already and post a link if you can.  

Q.  Is it post ban legal to use permanant loc-tite (I am not sure which color it is, but I know it exsists) to attach a muzzle brake to a threaded 16" barrel?

TIA  

G45

edited for spelling

A. ATF has never approved such an installation method.

ATF has approved the use of four or more equidistant spot welds, or blind pinning and welding the pin, or use of high-temp silver solder, or bead-welding over half the circumference of the brake.

Thanks!  

Can silver solder be done with a soldering iron, or do you need a torch?

high-temp (1100F) silver-bearing solder, applied with a torch.  The low-temp stuff would melt off during firing.

Wouldn't such high temps run the risk of affecting the temper in the barrel?  If that is the case, that wouldn't be a good thing!  And if that's the case, the ATF is probably aware of it, and likes the idea of possibly ruining the lowly civilian's barrel.  

Am I off here?

Can anyone tell me the correct technique for silver soldering on a muzzle brake?

Thanks,

G45   [>:/]

That's probably one of the reasons most mfgs choose to blind pin and weld over the pin - that's about the least heat you can apply to the barrel and still do an ATF approved type of installation.

 1. thoroughly clean threads of barrel and brake. 2. Apply brazing flux (white flouride) 3. Heat barrel and brake with acetyline torch, using a rosebud tip.  4. Metal is ready when flux turns clear.  5. Apply silver brazing alloy to joint.  It will not flow very freely, and needs to be 'painted' on. 6. Allow metal to cool.  7, Wash joint thoroughly with hot water.  Flux is corrosive.

Looks like I will have a smith do the work, I do not have the proper tools to do the job.  Thanks for all the help, now I know I am making the right choice by sending it to Kurt's Kustoms.


G45

use a set screw to attach your muzzle break and tack weld over the set screw hole, viola-permanently installed muzzle break, blind pinning with a threaded pin

It has been my understanding that a blind pin doesn’t need to be welded.
Being that the pin is blind, there is no way to drive it out.

I thought that welding was required when the pin wasn’t blind.

Am I in error?

to my knowledge, ATF has not approved a blind pin installation without also welding the pin.  A blind pin alone should be "enough", but ATF isn't necessarily amenable to reason.

Your tolerance for risk may vary.

Yeah, common sense and reason doesn’t seem to apply to govt in general.

I looked around last nigh, but couldn’t find anything “official” one way or the
other on blind pinning.  The letter on Bower’s board mentions welding and high-
temp silver, but does not say anything about pins, welded or not.

“Your tolerance for risk may vary.” Hey, I like that, can I quote you on that, oops,
guess I already did.

RK  

Some people think that soldering a brake will destroy accuracy - yet irregularly spaced welding at double the temperature is somehow okay, or pounding a pin in to apply pressure on one side of the bore is okay. The easiest is with Hi-Temp Silver Solder Paste.
These folks have it pretty cheap. Item #56

[url]http://www.silversupplies.com/catalog/silver_solder/solder.shtml[/url]

1. Clean the threads with a wire brush and degrease (some people use brake cleaner)
2. Clean the brake threads with a wire brush and degrease.
3. Put paste on the threads, screwed the brake on and back off until it’s properly aligned or “indexed”.
4. Heat entire assembly with mapp gas only, no oxygen for three minutes, color was a dull red in medium light, solder bubbles out the joint. That tells you it’s hot enough.
4. Let it cool slowly. Don’t stick it in water.
5. Clean off extra. I needed to scrape some excess off at the rear of the brake with a screwdriver and then brushed it with a brass bore brush.
6. Next time I’ll try it with the muzzle pointed down although you may not see stuff bubble out. Sounds like a good idea just as long as you don’t heat it past 3-4 minutes.

The thin peel washers melted or burned a little but overall it looks good.

What does the silver solder process do to the
surface finish of your barrel and brake?

My CAV COMP came with a roll pin and instructions.
[b]"For installation on a post-ban rifle
With hand drill, use hole in bottom of the comp to guide a 5/64th drill bitno more than 1/16th inch into the barrel. Drive the enclosed roll pin completely into the hole to permanently affix the comp onto the barrel."[/b]

I emailed them ( Cavalry Arms [url]http://www.cavalryarms.com/accessories.htm[/url] ) and asked if this was enough to be legal, or if I had to weld a bead over the hole.
They replied that as far as they knew, it was legal.[:D]
[img]http://wsphotofews.excite.com/014/UU/jD/lm/Ts50886.jpg[/img]

Does anybody have any experience with the CAV COMP, or with the legality of its installation on a post ban (especially the roll pin)?

Emailed whom?  Who said it was legal?

Great info in this web page, here is one link:
[url]http://www.cs.cmu.edu/afs/cs/usr/wbardwel/public/nfalist/atf_letter40.txt[/url]


DEPARTMENT OF THE TREASURY
Bureau of Alcohol, Tobacco and Firearms
Washington, D.C. 20226
JUN 18 1998            

Dear Mr. :

This refers to your letter of March 31, 1998, in which you ask about permanently attaching a muzzle device to various firearms.

A muzzle device, such as a muzzle brake or barrel extension, which is attached to a barrel by means of welding or high temperature
silver solder having a melting point of at least 1,100 degrees Fahrenheit, is considered to be part of the barrel for purposes of
measurement.  A seam weld extending at least one-half the circumference of the barrel or four equidistant tack welds around
the circumference of the barrel are adequate for this purpose.

A firearm having a muzzle brake, cap, or barrel extension permanently attached by those same methods to cover the threads on a barrel, would not be considered to have a threaded muzzle.
Please note, however, that any muzzle device or barrel extension which functions as a flash suppressor or grenade launcher would
still constitute one of the qualifying features of a semiautomatic assault weapon as that term is defined in 18 U.S.C. section
921(a)(30(B).  Industrial adhesive products are not an acceptable method for permanently attaching a muzzle device.

We trust that the foregoing has been responsive to your inquiry.
If you have further questions concerning this matter, please contact us.

Sincerely yours,
Edward M. Owen, Jr.
Chief, Firearms Technology Branch

Yeah, take it to a smith. If you don't know what you're doing, it's easy to screw things up.

The bigger question is . . . If the barrel is threaded, it's a pre-ban barrel. A threaded barrel is legal ONLY on a pre ban receiver.

If you want to put a threaded barrel on a post ban gun, you need to silver solder it. Heat can warp a barrel and/or the brake. That's a bad deal.

I would also be interested in this information.

Edited to be clearer...
Cavalry Arms said blind pinned was enough to be legal...