Any advise, yea or nay? I think I am developing another itch.

It's the only BP double caliber that can be loaded to sufficient power to take Cape Buffalo or Elephant. Get Graeme Wright's book on loading for it.

Go for it !!
I always wanted one and am really enjoying my 1875 Alex Henry. Be prepared an older rifle may be a bit of a project, with barrel and chamber casts necessary. But bullet molds are readily available and the steps to develope regulating loads well documented.
The process of developing an accurate, well regulated load is very satisfying.
Hope you go down this path.
Let us know what you find!
Larry

YES!!! The nitro for black loads are fun to shoot. Had a guy on the range comment that my "double" looked "heavy", told him I was shooting slugs, he seemed satisfied.

I really regret missing Mark Jones Nizam of Hyderabad's spectacular 577BP!!

David Powell and Cal Pappas also were successful with 4Bore, 8 Bore, 10 Bore, and 577-20ga... light Nitro loads!!

Go for it!!