Blind-pinned?

[22_Shooter 1,560]

In NY state, muzzle brakes are only allowed if they are permanently attached. I only knew of soldering it to get this done, but just read about "blind-pinning" to get the same effect. Saw it on ARFcom, but don't (can't) have an account there, so I'm asking here...............What exactly is blind-pinning?

Edited September 16, 2007 by 22_Shooter

[nalioth 405]

Screwing or pressing on your muzzle device (the really evil one, ya know). Drilling a 90 degree hole through the muzzle device into the barrel a short ways. Welding over the pin and grinding to normal muzzle device contour.

 

Thanks NY and CA.

 

Note 1: It's considered 'bad' to drill all the way through your barrel when doing this.

 

Note 2: Century disregarded Note 1 on several Cetme rifles.

Edited September 16, 2007 by nalioth

[22_Shooter 1,560]

OK, thanks for the info. So is it "safer" to get my barrel threaded and a brake soldered on? Or is blind-pinning a fairly easy task for a gunsmith? I don't wanna have my barrel mucked up if they drill too far.

[Etek 32]

Soldering is out of the question. You either have to Silver solder it, use four equally spaced welds, or weld at least halfway around the barrel in order for it to be permanent. This according to the BATFE

[nalioth 405]

As Etek points out: The 4 approved methods are

 

1) blind pinning

 

2) high temperature silver solder (1200 degrees or better, i believe)

 

3) tack welds at 12, 3, 6 and 9 o'clock

 

4) continuous weld of at least 50% of the contact area

 

If you get a good smith, he won't screw up the blind pinning. If you're gonna blind pin, you don't need to thread the muzzle, just find a press on muzzle device.

Edited September 16, 2007 by nalioth

[22_Shooter 1,560]

OK, thanks to both of you. You cleared a lot up for me.

[ArcFault 4]

I thought that blind pinning was just a pin press fit into a blind hole, the idea being that you don't have to solder or weld.

[nalioth 405]

I thought that blind pinning was just a pin press fit into a blind hole, the idea being that you don't have to solder or weld.

Not according to the alphabet gang in regard to firearms.

[ArcFault 4]

I guess that means that theres no reason to blind pin then. It's less work to tack weld or silver solder. Odd.

[cscharlie 107]

The more heat that you apply to your barrel, the more accuracy you will tend to loose.

 

When you blind pin, you can tig weld a little spot over the end of your pin inwich is a little recessed from the surface of the flash hider. It's too prevent it from being removable.

 

If you solder the flash hider, you need to use silver solder, that requires heating well over 1000 degrees according to the BATFE in order for it to be considered perm attached if I remember correctly.

 

The small weld over the end of a pinn would be applying less heat to the barrel steel. That is a good reason to blind pin.

 

Edted to add: After it's pinned, if you realy wanted to, you could grind around the pinn and through the weld and pull the pin out to change the flash hider. If you weld it directly, you might have to cut your barrel to remove it.

Edited September 18, 2007 by cscharlie

[hcpookie 0]

The information I've collected on Blind Pinning is here, originally found on the FALFILES:

 

http://pookieweb.dyndns.org:61129/AK/docs/...l/blind_pin.htm

 

HTH

[acercanto 6]

I wonder how hard/safe it would be to put your blind pin through the barrel at an angle so that it came out on the other side without entering the barrel, FSB style, like that. You could then weld both ends, file down, and refinish and nobody'd be the wiser... Hm.

 

Acer

[nalioth 405]

I wonder how hard/safe it would be to put your blind pin through the barrel at an angle so that it came out on the other side without entering the barrel, FSB style, like that. You could then weld both ends, file down, and refinish and nobody'd be the wiser... Hm.

 

Acer

I believe the alphabet boys specify a 90 degree blind pin. The actual regs do contain quite detailed specs.

[RDSWriter 5]

I wonder how hard/safe it would be to put your blind pin through the barrel at an angle so that it came out on the other side without entering the barrel, FSB style, like that. You could then weld both ends, file down, and refinish and nobody'd be the wiser... Hm.

 

Acer

I believe the alphabet boys specify a 90 degree blind pin. The actual regs do contain quite detailed specs.

 

I'd actually like to know the answer to this one... pinning all the way through and welding.

 

My supposition is that the method is probably okay or likely to be approved by the ATF as it would be as difficult to remove a pin welded in two places as it would a pin that could be drilled to remove the weld and then drilled and tapped to remove from the hole. Just write the Tech Branch and ask.

 

Funning thing though... is that (1) it would be harder to pin all the way through than to pin the 'approved' blind way, (2) it would require cleaning up two welds, and (3) it would apply more heat to accomplish.

[Twinsen 86]

Screwing or pressing on your muzzle device (the really evil one, ya know). Drilling a 90 degree hole through the muzzle device into the barrel a short ways. Welding over the pin and grinding to normal muzzle device contour.

 

Thanks NY and CA.

 

Note 1: It's considered 'bad' to drill all the way through your barrel when doing this.

 

Note 2: Century disregarded Note 1 on several Cetme rifles.

You forgot the even worse state of CT. We can't own any AK varient in 7.62 and need to do everything else you guys do. We have no magazine restrictions though. I can't wait to get a 74 style MB on every AK I own.

[loner42 6]

A properly installed blind pin should not have to be welded over as it would be next to impossible to remove without drilling it out. I'm talking about a .0005- .001 press fit.

 

The letter from BATF to Wilson was regarding using a 6-32 set screw not a press fit pin.

 

If i were doing it, i'd install the pin leaving it a little proud and file it flush and call it good.

 

I'd like to see someone remove it without drilling it out..................

 

My 02 centavos

[hcpookie 0]

HRM you guys don't follow links do you? OK here you go:

 

Original Link Here:

http://www.falfiles.com/forums/showthread....ht=blind+muzzle

 

 

"...printed from the Wilson Combat website back in April 2000. The source is the ATF, in response to a letter about the attachment method from Wilson Combat. The author is Edward M. Owens (hence the EMO at the top) the now-retired head of ATF Firearms Tech Branch."

 

 

/Begin quote:

 

DEPARTMENT OF THE TREASURY

BUREAU OF ALCOHOL, TOBACCO AND FIREARMS

WASHINGTON, DC 20226

 

FEB 2 2000

 

903050:EMO

3311

 

Mr. XXXX XXXXXX

XXXXXX XXXXXX

XXXX XX XXX

XXXXXXXXXX, XXXXXXXX XXXXX

 

Dear Mr. XXXXXX

 

This is in reply to your letter dated December 28,

1999, in which you ask about permanently affixing

muzzle brakes your firm produces to barrel muzzles

of "post ban" AR15 type rifles.

 

You indicated that the barrel muzzle will be threaded

to accept the muzzle brake. The brake will be screwed

to the barrel muzzle and a 3/32 inch hole .030 - .050

inches in dpeth will be drilled into the barrel wall

using an existing set screw location in the brake as a

pilot hole. A 6X32 TPI set screw will be installed

through the pilot hole and into the described blind

hole in the barrel. The set screw hole will be welded

over after installation of the screw to permanently

affix the brake to the barrel. Excess wild will be

removed and the muzzle brake refinished to conceal the

location of the weld.

 

The above described procedure has previously been

approved for use in permanently affixing muzzle

attachments to rifle barrels. An AR15 type rifle

barrel having a muzzle brake affixed as described

above would no longer be considered to have a threaded

muzzle provided that deep penetrating steel fusion

welding is used.

 

/End quote

[dk8019 5]

This is bringing up an older topic, but I've seen muzzle brakes attached this way to maintain barrel length. It's impossible to remove without drilling, yet it seems there's a lot of insistence on welding over it. Any other input here?

 

A properly installed blind pin should not have to be welded over as it would be next to impossible to remove without drilling it out. I'm talking about a .0005- .001 press fit.

 

The letter from BATF to Wilson was regarding using a 6-32 set screw not a press fit pin.

 

If i were doing it, i'd install the pin leaving it a little proud and file it flush and call it good.

 

I'd like to see someone remove it without drilling it out..................

 

My 02 centavos