I have been eyeballing a sxs 10 gauge black powder shotgun for a while.
I have yet to have the chance to shoot one, however everything that I gathered is that they perform like the modern bore equivalent below the listed black powder bore- dunno if I worded that right...
And now I may be completely wrong, but from what I gathered a 10 gauge bp shotgun will have the oomph of a modern 12 gauge 2 3/4" load, a bp 12 gauge will perform like a light modern 20 gauge round and so on.
I've only seen a handful of bp shotguns in person, but I like the pedersoli guns, however there's a ton out there.
Greens gun shop on north whidbey Island every now and again has one come through, all the ones I've handled were feather light and pointed beautifully.... how they shoot is anybody's guess.
Id reckon some out there are going to have barrels that shoot completely different than where you aim, I don't see a lot out there having matched true-to-point-of-aim barrels but I've always wanted to put on the wool and hip boots and do a duck hunt with burlap and cork home made duck decoys and shoot a black powder on a hunt, although that brings another question as to whether or not barrels are steel safe. I think the new production pedersolis are steel safe, but anything else might be something to look into. I know a lot of black powder shotguns were made thin and the loads were kept relatively light
All depends on what you intend to use it for I suppose
https://www.davidepedersoli.com/en/product/waterfowl-side-by-side-cal10-cyl-impr-cyl If I had to get one bp shotgun that would be it right there. New enough to handle modern rules, old enough to be timeless