safe barrel wall thickness after tennons installed

[StevenV]

I have a question about safe barrel wall thickness after installing tennons. With a tennon base of .050" look at the photo, using 3 pins for a 38" barrel I have a barrel wall thickness of .120 at the thin location subtract .050 and your talking .70 wall thickness. With 4 pins the two thin locations .136 - .050 = .086 wall thickness and .114 - .050 =.064 thickness.
Questions:
1.) can tennon base be thinner, perhaps .040 and still be functional ? ( I'll gain some barrel thickness going with a thinner tennon base)
2.) is 3 pins on a 38" barrel sufficient ?
3.) do you think the wall thickness is an issue after installing tennons?         Steve

[G_T]

It might be hard to get people to say what is safe. Perhaps some will say what may be unsafe.

The dovetail for the tannons does not have to be full depth. Cut it shallow, and make a cold chisel for peeling up the edge a little. Then insert the tennon, and firm up the edge gently with a punch. If in doubt, then silver solder. That sort of technique can allow you to leave greater wall thickness.

Gerald

[Mauser06]

Take the tennons down.  And like was said, silver solder if you think it's needed.


A tennon essentially holds the stock to the barrel. They don't need to bear a lot of weight/force.


I've seen arguments against soldering before saying it can warp a barrel...the stuff I use melts at 420 or something. I try to heat around the barrel somewhat evenly but I can't see it doing anything to the barrel... doesn't even cause a color change. Higher temp stuff...maybe an issue.

I'd avoid putting tennons into the waist of any barrel if I can help it.

As far as 3... should be fine. One near the muzzle.  One 10-12" or whatever from the breech, and another somewhere near the middle of those 2.

[elkhorne]

Mauser,
What brand/type of solder do you use that melts at 420 degrees? Thanks
elkhorne

[Scota4570]

Lead solder.  Old fashioned plumbing or better rosin core electronics solder works fine.  Do not silver solder.  Silver solder melts a around 1200*F. 

Loctite 638 or 680 are very good for this type of thing too.  The shear strength of these is comparable to lead solder. 

[Daryl]

Brownells Force 44 seems an excellent solder for all gun work.

[Ky-Flinter]

StevenV,

Take the tennon base down to about .030".  Three tennons is plenty for a 38" barrel.  Avoid putting a dovetailed tennon in the waist.  If the tennon has to be there, solder that one on. 

Here's a good discussion on the topic.... http://americanlongrifles.org/forum/index.php?topic=51051.0

BTW, in your diagram/measurements, you didn't account for the depth of the rifling.  .540" is the bore, add the rifling depth to that.

-Ron

[45-110]

Soft Solder............Not silver which needs way more heat with the possibility of distortion, then there is the scale clean up.

[Hawken62_flint]

I agree with Daryl.  Brownells Force 44 and their liquid flux works great and melts at a low temp. You can use one of the little butane torches to melt it.  It works great on tennons and on sights on round barrels also. 

[Mauser06]

I've been using silver bearing "Solder-It" paste.   


Comes in a syringe which I like. Easy to put it where you want it. 

Just looked. "Flows at 430 degrees". Remelts at 500 degrees.

I've used it for a few things now on 2 builds and if seems like it is very strong.  Easy to use too..I've never soldered anything before and this is easy as cleaning the area, applying it, and slowly heating the area.  You can watch the heat start working on the product and when the paste starts melting, that's about enough heat for it to flow. 

[Mr. Bubbles]

I thought that rosin core was for soldering things like electric wires, and acid core was for everything else.

[Mauser06]

No idea....I saw it recommended here before and I needed to solder a sight and tennons on a round barrel.   


If it's "wrong", well, ok.  Seems to be holding very well. 

[Hungry Horse]

StayBrite is another low temp high strength solder that melts somewhere between 400 and 500 degrees. I use it for lugs,  front sights on fowlers, and round barreled pistols. It like five or six times stronger that lead solder. It available at hobby shops.

 Hungry Horse

[Scota4570]

I thought that rosin core was for soldering things like electric wires, and acid core was for everything else.

Tin the parts with acid flux, steel wool and whatever solder.  Wash the parts to elimante the acid residue.  Coat with liquid rosin flux or rosin and alcohol.  Jig them up.  Heat, add rosin core solder as needed.

Acid core solder and acid flux will cause future corrosion that may compromise the joint. 

Or maybe I over think it.  That is what I do based on the frustration of re-soldering several  shotgun ribs with corrosion under them.  I also have rosin and rosin flux on hand. 

[Clark Badgett]

This is a subject that I have seen differing opinion on. Some say that the shallow dovetail in the waist of the barrel will never be problem, others will say other wise. Personally, I don't see how a .020"-.030" dovetail would effect strength when there is about .1" of steel left.

I'm no expert by any means, even though I do work with metals every day. Really, there is a lot I don't know. Are there examples of barrels failing and/or bursting in the waist area when lugs are properly cut in?

I do know I have had a problem with my soldered lugs coming loose. I'm about at the point that I'm willing to risk dovetailing them all from this point.

[sdilts]

I second the Solder-It paste. It's the easiest solder I've used. I've used it on ribs, sights and thimbles and have had no problems. You can find it at Home Depot.