As was written-a solution for a nonexistan problem.
The greatest problem which we have nowdays is the simple fact that the wall thickness, as well as the cap lenght is a bit less than back in the day. There´s a serie of photos of a loaded 1858 revolver floating aroud the internet, which was dugged up on some battlefield, in quite decent condition and showing the caps clearly.
Esp. the wall thickness allows for excessive bursting and then jaming the action. And considering the waterproofing-more PC (hell on that somehow...) is to put some beewax dilluted either in turpentine oil or in "white spirit of petrae oleum" aka gasoline nowdays, let it dry (few seconds), put the caps on and dip a tear of the dilluted beewax over it again. You can drop the revolver into a bucket of water for few days and the only concern about the powder moisture ratio comes from what you use for lube in front of the balls and how completely are the chambers filled with it.