....are IMHO one of the most fun things you can do legally these days.
Take an Uberti (or Pietta or Navy Arms or whatever) repro cap and ball revolver, add an R&D cartridge conversion cylinder-
And you have a nice repro cap and ball pistol that shoots modern ammo loaded to cowboy, low pressure specs.
The one in the picture above is an Uberti 1861 Colt repro converted to fire .38 Long Colt.
Which ammo, thanks the cowboy shooters, is now readily available.
Eveyone who shoots mine is just crazy about it.