I kicked around the weld idea, but as the fracture in the metal would still be there, I'm doubtful. If used as is, it will be full of solder and lug, not that it would hold much.
I do know that I've seen some pictures of fowlers (originals) that were absolutely paper thin at the muzzle. And those were old barrels, not new modern steel.
I wish I knew what bore/groove diameter was on the barrel. Tried to measure with my calipers, but didn't want to scratch anything up (in case I keep it) so I was pretty tender about it. I didn't count grooves, but I guess it is an odd number as every time I tried to position the calipers, I had one tooth on a land and the opposite on a groove. A .530 ball would roll around in it, I do know that.
I did read off of Rice's site that they do rifle .016" deep on their round bottom rifling.
Sooo, if the barrel is .815" at the dovetail, and I cut the dovetail .060", and if it's .540" bore, with .016 grooves, best I can math out, that'd leave about .065" under the rifling groove. Though as I said, I'm not sure what the actual bore/groove diameter is.
Like I've said before, I can't imagine that the vent liner is much thicker than that, with a lot more pressure against it (though there's no ball running through there).
I've also wondered, while Rice's machining seems consistent, would a new barrel match (with maybe a slight degree of fitting) my barrel channel (Dave Keck did it, if I'm remembering right)? I suppose I could rough in a new breech lug to fit the inletting that's already there. I was going to glass that in anyway a)for strength and b)to cover up my lackluster inletting of the tang.