Barrel tennons...

[Mauser06]

I'm starting my next build....

I'm questioning whether I should solder barrel lugs on (especially in the waist) or if I can cut dovetails. 

The barrel is a Hoyt .582cal with his normal rifling. I can't get a good measurement of the rifling depth. At the waist it's measuring right around .810.  leaves the barrel walls at .114"..minus rifiling so probably right around .100" give or take a few thousanths.

I don't know that I'm comfortable dovetailing into that...is there a "rule of thumb"?? 


Thanx!   Trying not to ruin the barrel...or blow myself up.  I have no problem soldering them on.. actually probably quicker and easier...but a little more inletting. 

[stikshooter]

That"s easy call Bob Hoyt he knows exactly the answer (he built it) Ed

[G_T]

Best to ask Hoyt of course, but I have been told the dovetail really only needs to be about 1/16" deep to hold (from Rice barrels when I asked about dealing with thin wall barrels). You could do that in the thinnest region but use a more normal depth elsewhere.

I'd be concerned soldering in an area that is thin enough that you have concerns about dovetails. It is hard to heat completely uniformly and cool the same. And if the barrel isn't stress relieved adequately... It might warp.

Gerald

[B.Habermehl]

I hav always soldered Underlugs at the barrels waist. Never had a barrel move. I use modern plumbing solder and flux. It takes me about 15 minutes tops. Be sure to oil the bore after the job is done. BJH

[Huntschool]

Don't know that this will help but TOTW advertises for their staple lugs you should drill .073-.075 depth and allow .050 material between the bottom of the drill hole and the bore, if you use staple lugs.

I have personally never needed to worry about the depth clearance on previous guns but I am about to build two that that measurement will be critical if I go with the staple lugs or even if I cut a dovetail.

Just some info......

[T*O*F]

I have a dumb question.  Why does your tennon have to be exactly at the thinnest part of the barrel?  Can't you alter your layout to space them differently?

[davec2]

I learned from others here and now only dovetail to a depth of about 0.035 (~ 1/32").  Plenty deep enough to hold the thin wood of the forearm to the barrel.  Here is one that came out about 0.038" deep.  I dovetail in the lugs even at a thin waist.  Even with deep (~0.015") rifling, it still leaves ~0.085 " wall 3 feet down the barrel.

[Huntschool]

Not to jack a thread.....

Does anyone try and get their lug pins to line up horizontally on a swamped or tapered barrel and if you do..... how do you do it.  Could be a stupid question as I think I know what to do having done several,  but....

Thanks

[Mark Elliott]

Don Getz once told me that the rule of thumb is to have a minimum of .100" wall thickness.    I make my dovetails about .040" and generally follow Don's rule of thumb.   However, Rice says on their web site to not put a dovetail in the waist of one of their barrels and I don't.    I will solder a tennon on if it must go into the waist of a thin swamped barrel.     

The problem with just not putting a tennon in the waist is that the waist on most modern swamped profiles is fairly long; like in the 10" range.    One of my tennons generally falls in that area.     

The current rifle I am working on is has a close copy of an original barrel from an E TN.  rifle; and is 45 cal and no thinner than .920".    That gives me plenty of meat for a dovetail anywhere I want to put one. 

[Mauser06]

Like Mark said, the waist is fairly long...1" at the breech..  .900" or so at the muzzle.  Doesn't leave a ton of meat there with a .58cal. 

Rivers are blown out and I couldn't fish this evening.  Going to eat and back to the bench.  Slim dovetails aughta work on it... avoiding the thinnest part...but I will work on my layout and take measurements before cutting anything.  Probably all I will get accomplished tonight is working on the layout. Maybe work on the tang.

[Acer Saccharum]

The tenons aren't doing anything but holding the wood to the barrel, and keeping the ramrod safe within its ferrules and grooves. The tang bolt and first tenon attach the barrel to the stock, the rest of the tenons hold the stock to the barrel.

You don't need much dovetail depth. Anywhere from .025 to .04" is plenty. Fold up your own tenons from .032 or .04 sheet metal. The cast tenons make you think you need to make deep and mighty dovetails.

I create the flat plane for the tenon to sit on with hacksaw and file, then with a SMALL chisel. maybe 1/8" wide at most, start lifting the dovetails. I work this slowly across the barrel cut, tapping as I go. Patience is the key, but slowly you'll see the material rising and the dovetail forming underneath.

The method I use does NOT employ a wide chisel that must be struck with great force, chancing the distortion of the bore underneath.

Once your tenon fits close, tap it into position, and then peen the dovetails down onto the tenon, and file everything smooth.

[Elnathan]

I did an experiment a number of years back. I made a underlug out of ~1/32 sheet steel and dovetailed it into a scrap of Green Mountain barrel, clamped the underlug in the vise, grabbed the ends of the barrel with both hands, and lifted straight up with all the strength I could muster. The vise was screwed into an old desk weighing several hundred pounds, and at a height I could get my back into the lift, so I could put quite a bit of force on that underlug. The end result was that I couldn't pull it free, at least not without twisting it (which I didn't try).

My conclusion is that, at least in a Green Mountain barrel, a dovetail 1/32 or maybe even a bit less will hold under any force that a barrel is likely to encounter under normal conditions, and that the forearm will likely split before the dovetail fails.

[Davemuzz]

Converting to decimal, 1/32" = .03125". On my Leman build I cut into the barrel for tennon's of .070", which converted to fraction is roughly 5/64".

I felt that was plenty of depth to hold the 3 tennons I have in the 38" barrel.


FWIW

[jerrywh]

 I have done it both ways but I make my dove tails no deeper than .040. In a black powder gun there is very little pressure that far down the barrel. Remember as the bullet moves down the barrel the pressure drops. The bigger the bore the less  the pressure. I doubt if any body on this forum knows more about this than Davec2.  He is actually a rocket scientist.  However either way is OK.  I have built guns that only had a thickness of .032 at the waist and proofed them with scary loads multiple times. Like I said the pressure at the waist is pretty low.

[Turtle]

I have a tool from track that makes it easy to raise metal at the ends of the dovetail. One of the reasons I got a kebler .45 mountain rifle with that lovely thin walled A weight barrel is that the dovetails were already cut-saving my worry.
                                                                Turtle

[P.W.Berkuta]

Like most others here I also inlet my barrel tenons between 0.030" to 0.040" deep depending on the barrel. I will also solder on a tenon at the waist if necessary. My rear and front sights are inlet about 0.040" or less.

[TommyG]

I make all mine from .040 brass sheet.  For the waist tenon, I take the base thickness down to around .025 by using a piece of glass with sandpaper.

[moleeyes36]

I make all mine from .040 brass sheet.  For the waist tenon, I take the base thickness down to around .025 by using a piece of glass with sandpaper.

TommyG,

.040 sheet brass is what I use also.  In Mike Brooks' tutorial, he shows how to make and install them for those that haven't tried it.

Mole Eyes

[davec2]

I think the experiment done by Elnathan tells you everything you need to know about keeping that thin wisp of a wooden forearm nailed to the barrel.  And Jerry is correct about the pressure in the barrel by the time a round ball gets to the waist of the barrel.  Solder on a lug if it makes you feel better but a .030" deep dovetail is all you need and won't effect the pressure capability of the barrel.  Besides, you are only cutting the dovetail at one point tangent to the bore, not all the way around the circumference.