Question, "Blind Pinning" What is the accepted method.

[jackofall]

I am currently working on a couple of gunsmithing projects.
Both of which have barrels which must be lengthened in order to be legal.
The two common methods are either silver soldering the muzzle brake to the barrel, or blind pinning.
I have chosen the latter, and I would like input on the methods commonly used.


Thanks,

 

[Tony Wells]

We do have a couple of licensed Smiths on board, so I'm sure they could give you the real lowdown on it. My understanding is that the pinholes are drilled through the MB or FH, and only partially through the barrel. Once they are pressed in, they must be welded, preferably TIG, so they are not removable. That's the point. The silversolder is more straightforward, but some people (me included) don't like the idea of putting that much heat on a barrel.

 

[Highpower]

The silversolder is more straightforward, but some people (me included) don't like the idea of putting that much heat on a barrel.

Add me to the list of "some people" please.... )

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. 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. 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furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and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.

 

[JB Enterprise]

Hey Willie long time no see, been busy hunting season and stuff is breakin, any way the way that I do it is, and I presume that the guy is doing an ar with a 14.5 inch barrel measure from front of bolt face to furthest point of barrel I like 16.125 inches just to b sure then use an 1/8 endmill drill through brake and no more than half way through barrel install 1/8 drill rod piece or small dowel pin just a little proud of surface fuse w tig and apply cold blue. I do not flatten weld just to be sure that people know that it is permanently attached.

Justin Bowerman
jB Enterprise
07 FFL IN CEN CA.

PS this method is accepted by the B.A.T.F.E.

 

[Highpower]

Hey JB, being busy hunting is a good thing!

Question for you:

I have read somewhere that ATF has a minimum torque requirement that it takes to break loose a muzzle attachment once it is pinned. I'm guessing that a piece of wire coat hanger isn't going to pass for an acceptable pin. :nono:

For the life of me I cannot find any documentation from the BATFE that covers this. Your thoughts?

 

[JB Enterprise]

Hey Willie I don't know about torque spec but I know. 125 drillrod is acceptable due to a atf variance letter that one of my buddy's have so that is what I go by seems to work for everything pretty well. By the way I do know that it taks alot of force to shear drill rod.
Justin Bowerman
JB Enterprise

 

[Bobby Bailey]

Justin pretty much describes the way we do it. As he says, we don't try to hide the weld. That way anyone can tell it is legal.
Bobby