doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Thoughts on an action going off face

Thank you, Dennis. Information like that is invaluable. I'm a bit confused though, as my gun forend still has a tight fit. When you put it in place the latch will not seat itself without squeezing the forend to the barrels with some hand pressure. Maybe I am misunderstanding your meaning about the fit?

SRH

One phenomenon seldom discussed by us shotgun lovers is the Poisson effect that manifests in pressurised thick walled cylinders. The breech end of shotgun barrels is a thick walled cylinder, the walls being thicker than one tenth the diameter.

A thick walled cylinder contracts lengthwise and expands radially in response to pressure and then reverts to its original length. This is a fast process obviously and happens at the same time as the rearward flexing of the action. It is reasonable to assume that the two processes, chamber shortening and action flexing and the recovery, pound the chamber ends of the barrel thus creating a gap.

In some guns you can sense the pounding by feeling for the raised burr along the chamber ends.

The above is I believe the cause for coming off face and not the wear from opening and closing. But it is a personal opinion, not widely accepted.

Update. I took bushveld's advice and found some HVAC aluminum tape and fitted a piece to the hook. It mic'ed .003". One piece of it completely put the gun back on face, with absolutely no light visible between the right barrel breech and the standing breech. I was really surprised, as this showed that the wear was really at the hook/pin joint. The gun, with the .003" shim on the hook, is as tight as a brand new gun. That tape is some really tough stuff it seems. My plans now, since I have been informed that tiging the hook is out, is to shoot it for awhile with the shim in place to see just how long it lasts and whether or not it "wears in" and loosens up again.

I've messed with cutting shim stock and getting it to adhere it to the pin on guns before, but this tape stuff is so much easier, if the thickness is right. When fitted properly it is all but invisible, no kidding, and the adhesive on one side of it makes it a natural. I intend to see how long it lasts before going any further with repairs.

Thanks everyone for the valuable information. Especially bushveld and Dennis. You may have saved me considerable grief, not to mention funds.

SRH

There was a Double Gun Journal article on a guys Nitro Special that had a brass shim on the pin, that lasted for about a decade of duck hunting, with the big number rounds, which was then sold to another guy, who was aware of the repair, and used it for many years, for the same type of use, with the same repair. He had paid $10 or $20 bucks for the old gun, and tried the repair, and found it worked just fine for his use.
A sheet of ordinary paper mics at around .004, and usually stays in place just fine, if you don't need to tear the gun apart to clean it. I like the notion that the paper will hold some oil while doing it's job, but, anything that takes up the slack will likely be OK.
Sorry to hear about the limitations on options for repair. Well, a money repair, at any rate. The free one will work just fine as long as you want it to.


Best,
Ted

Thanks, Ted. Sometimes knowing what you can't do is worth more than knowing what you can. This HVAC tape is some tough stuff. I put a piece on, rather sloppily at first, just to try it and see how it fitted up. After I saw how well it tightened things up I went to remove it and cut another the exact size needed. I had to scrape the stuff off the hook with a knife blade! When you clean the hook thoroughly with alcohol, as bushveld recommended, then apply the tape it sticks better than you could imagine. A little grease to lube the pin/hook joint and it's good to go.

SRH

I didn't exactly understand the Caveat against the TIG repair of the hook. I have been under the impression that brazing had a higher melt point than did Silver Solder. Maybe I misunderstood what the poster said on that , but I recall him saying the lug was brazed rather than Silver soldered thus couldn't be TIG'd. The Tig is actually hotter than either but if the person doing the TIG knows what they are doing they shouldn't melt either as the TIG heat is concentrated at the repair spot & can be kept from spreading into the joint. I Do not know Stan personally, but I am of the impression he isn't going to let anyone ahold of this gun who doesn't know what they are doing.

The BSS has the barrels and ribs silver soldered together, and the barrels are chopper lumps, each half of the lump is joined with brazing material that flows at a higher temperature than the silver solder when the ribs are soldered. The weld puddle gets contaminated by this brazing material, at least with TIG. Laser may not have this problem. This info came to me from someone that used to work for Browning, and also was my experience.

Thanks Dennis;
I see the problem now. I am not a welding expert, but suspect either mat'l would contaminate the weld. The problem is that it is Chopper Lumped & thus one would be welding across the seam with the filler mat'l.

Exactly, Miller. I can see the seam under close inspection.

T'would seem this would be a candidate for pin replacement, if indeed it has a removable hinge pin. Or, maybe a dovetailed "shoe" liner.

I'm just happy that I can continue to shoot it with the "shim" until I gather all the information to have a proper repair made, by the right person.

SRH

Stan, I have done this with three guns and they have lasted well. My old M 21 was slightly off face and I shimmed it a couple of years ago. I used high tensile Permatex to hold it. I also have used a shim FROM a beer can (LONE STAR BEER OF COURSE) AND IT WORKED WELL.