Placement of underlugs and the thinest part of the barrel

[GaryJ]

I have a question concerning the placement of barrel lugs.  I have a 41", 40 caliber swamped barrel.  I wanted to use 4 barrel underlugs - The first lug from the breech at 9", the second at 19", third at 29" and the fourth at 38" which is only 3" from the muzzle.   But, the 3rd lug from the breech would be placed in a section of the barrel that is only .67" wide. If my math is correct, that means that the width of metal available is .135" (.67-.40=.27 divided by 2 =.135) and the lug depth is .05.  That only leaves .085" of metal.  Doesn't sound like much metal left but I don't know.  Should I eliminate this lug and use only three lugs?  Will that leave too much distance between lugs? Or, should I reduce the depth of the base of the lug and make it very shallow?  If I eliminate the lug, I would think there is a possibility that the wood might pull away from the barrel.  I'd appreciate some suggestions.  Thanks, Gary.

[Nate McKenzie]

Three would do fine or you could solder the scarey one with high strength solder such as Brownell's  Hi-Force 44.

[Larry Luck]

Gary,

Most of us start off thinking the purpose of the barrel lugs is to hold the barrel to the stock.  When you think about it, you are really holding a pretty light and flimsy piece of wood to the barrel, at least from the entry thimble to the muzzle.

Three underlugs should be sufficient.  If you want to use four for stylistic or other reasons, the dovetail for the lug in the thin section does not need to be very deep, and you can upset the ends of the dovetail with a sharpened cold chisel (or the TOTW underlug tool) and/or solder the lug to the barrel.  Lots of ways to skin that cat.

Hope this helps.  

Larry Luck

[billd]

Solder it on.
Bill

[smylee grouch]

If one was to solder it on, do you think a clean dry bore would be better?  I soldered ribs and lugs on before and ended up having to clean alot of scorched oil out of bore after I was done.   Gary

[billd]

I wipe the bore dry of any excess oil but don't really scrub it out.

[Nate McKenzie]

Yes. Clean dry barrel then re-oil it when done. Use Bronells recommended flux for Hi-Temp 44 solder. Propane torch is good for heat. Don't overheat to point of turning color.

[Dennis Glazener]

.035 is plenty deep for a barrel tenon and that leaves .100 which is fine for barrel wall thickness. But I usually solder on the one in the thinnest section of an A profile .40 or a B profile .50 cal.
Dennis

[Jim Kibler]

Cut the slot .020 - .025" deep and form the dovetails with a chisel.  This raises metal upward and provides for plenty or strength with the depths suggested.  After the dovetail is inserted, flatten the raised material with a punch to lock the tennon in place.  I know people seem to like solder for this application, but I don't believe this was a technique generally used in 18th century work.  The method described is simple, produces a result that is neat, plenty strong and historically correct.  What more could you ask for?

[Acer Saccharum]

The tenon at this point is holding the wood onto the barrel, not barrel to wood. The barrel is the structure. The wood is just a slip, so you don't need a lot of strength to hold it in place.