A bit more on the barrel question

Original .50-70 barrels were a nominal groove diameter of .515", modern are mostly .510.  Original twist rates were around 1-in-42", most new are1-in-26" so can handle longer bullets.

Once I actually see the barrel and see if it can be lined, that may settle things if it can be.  Otherwise, new it is.  I don't have access to a lathe this size(know a couple of people who do), and was hoping to find one contoured, just needing threading, chambering, and dovetails cut.  Then I stared looking.  The only .50 barrels I have found so far are either for muzzleloaders, or .50BMG.  Neither Shilen, Green Mountain, or Shaw make a .50, either at all or with this pitch.  Dixie and Gun Parts, nope.  Few other makers, no joy.

I'll keep looking.  Comes to that, may have to convince to go to something that can be found without a 'And for only X-hundred more we can make you a custom!' situation.  

This is as frustrating as finding out decent quality flintlock rifle kits are more expensive than the so-so rifles out there.