I have found that most of the replica black powder firearms take the #11 cap. One thing that I would recommend if you haven't shot a black powder revolver is to buy some Ox Yoke wonder wads to go over the powder. If you use them then you don't have to grease the cylinder openings to prevent a chain fire.
If you're lucky enough to be on private land and can leave your stand up during the off season you can tie an old piece of cloth or something of the sort to your stand. I like to use an old camo bandana that I have. That way the deer get used to the movement and eventually don't bother even looking up when there is slight movement. This may just give you the time to draw your bow or raise your gun without being detected.