Dunno how far your curiousity goes with BP but it's a fascinating subject for me. BP is best suited for muzzleloaders and cartridges with long straight cases but I guess it can be made to work for some others as well. It's important to realize that the bullet must at least touch and better yet compress the powder charge. As mentioned above I'd avoid using it in gas operated autos unless you really enjoy detail stripping.
Cleaning isn't really that big a deal, I've been using Windex with vinegar followed by Bore Butter for years in my smokepoles. With my Sharps it's a 10 minute cleanup, with a c&b revolver it takes a little longer because I like to remove the nipples. The cleaners used for smokeless will just make a mess with BP, the so-called BP solvents are just as bad, IMHO.
I wouldn't use it in a modern bottleneck rifle cartridge unless I wanted a reduced load but even then there are better ways to go about it.
If you're curious about how well BP really works try it in a cartridge designed for it. Muzzleloaders and c&b revolvers are loads of fun as well.
Forgot to warn you, BP shooting can be addictive and no 12-step program has been shown to be effective. Try it at your own risk!
