Chubber,
I've been using a 50/50 mix of Simple Green & water for over a year - the stuff works great! <img src=icon_smile_big.gif border=0 align=middle> When shooting CleanShot powder, I can have the gun clean in 1/2 hour with this mix if I'm in a hurry. One word of warning though, when using water in any cleaning mix, make sure you remove all of it before oiling the gun and putting it up. I usually hit the bore with a patch of denatured alcohol to help evaporate any remaining water or soap residue, and then oil for storage.
I also sometimes use a product sold as MPro7 black powder/corrosive cleaner & it works great too. It is an organic, biodegradeable cleaner originally designed for the aerospace industry. It does make cleaning easier (less scrubbing required) than with soap & water mixes.....but it ain't too cheap (about $2 an oz in spray form).
There are many options on cleaners (depending on how much you want, or DON'T want to spend) - but I do advise staying away from any product with petroleum derivatives in it.......such tends to "gunk" up the bore & breech over time.
"Every moving thing that liveth, I give unto you as meat" (Gen 9:3)
Trust God..........but keep your powder dry!