As said above, you should have no problem shooting BP cartridges with your guns.
I shoot a BP sub (APP) exclusively in all my CAS guns mostly because I can use regular wax lubed bullets for reloading as opposed to having to use SPG lubed bullets (or similar lubed bullets). I just have a lot of regular bullet heads on hand right now. APP (American Pioneer Powder formerly known as "clean-shot") puts out a lot of white smoke but no flame. Real BP, like GOEX puts out plumes of smoke more of the grayish type, but visible flames fly out of the muzzle as well (very cool). When I run out of my bullet stock, I will be switching to the real stuff.
As far as clean up goes, there is good news and bad news. The bad news is that you do have to clean your guns the same day you shoot them.
The good news is that they clean up faster and easier when shot with BP or subs then they do with smokeless powder. I just remove the cylinder, and stick the forcing cone right under the faucet with very hot water pouring through the bore. Same with the cylinder. A couple of squirts of balistol, windex, or weasel piss (3 part mixture of hydrogen peroxide/Murphy's oil soap/rubbing alcohol), a couple of passes with a bore brush, and re-flush with the hot water.
The hot water evaporates fast, and I usually only need run a dry patch through the bore and chambers one time to dry. Wipe down the frame, apply a thin coat of balistol or weasel piss to all surfaces, and put 'em away. This all takes about 5-10 minutes per gun. Real fast and easy once you get the hang of it.
Hope this helps,
DS