I've seen an original 1860 that was cased with components for both cartridge and percussion firing. I believe it was a Thuer conversion. There was a person I met at a gunshow in Minot North Dakota that was modifying repro 1860's to use the Thuer conversion a few years back, he was displaying them at the show but I don't believe he was selling them. If you are a good machinest it probably wouldn't be too difficult to modify one yourself.
I thoroughly disapprove of duels. I consider them unwise and I know they are dangerous. Also, sinful. If a man should challenge me, I would take him kindly and forgivingly by the hand and lead him to a quiet retired spot and kill him.
- Mark Twain