Graf & sons, Powder, Inc., and the Maine Powder House are the three suppliers that come to immediate mind for buying black powder over the internet. There is a $20.00 Haz Mat fee added to any purchase, so that it just makes more sense, to find other flintlock shooters and split a case order. That reduces the total price per can of powder downward. A case contains 25 lbs. You can buy less, but the same $20.00 fee has to be applied to fewer pounds, meaing that each pound will cost you more. Check the Links section in the Member Resources section on the index page here. Then contact the suppliers and compare prices. You may be able to find someone close to you that will charge you a bit less for shipping. Some people can buy powder in bulk lots of 25 lbs. and save even more money. you have to supply your own containers when splitting a shipment up. YOu can legally have #50 lbs shipped to you with each shipment, and if you are a member of a black powder club, then that is the way to go.
The good news is that black powder is going to cost you less that that Triple 7 costs.
Oh, relative humidity has a lot to do with how much crud sticks in your barrel. In dry winter months, or up in the high plains and mountains, where the relative humidity is very low, you have to clean between shots, or the crud builds. It really isn't different if you use a substitute powder or Black Powder on that issue.
Look at this way: If you are going to shoot, and hunt with a single shot, muzzle loading rifle, you are not likely to get a second shot off at any game. You therefore have chosen consciously to " Handicap " your hunting experience to find out how it felt to be a hunter back when this was the best technology available. Forget about repeating rifles. For get about fast second shots. In this context, calling any second shot, no matter what safety corners you cut to load the powder and ball faster, is anything but FAST! Take your time, wait for the right shot, pass on the poor shots no matter how many hours are left in the season, and make accurate shooting your prime goal as a BP hunter. When you do bag game, the pleasure you experience will be immensely more satisfying than if you do as so many other men seem to want to do, and that is to cheat themselves of this experience by cutting all kinds of corners, from shooting zip guns, to loading NON-black powder propellants, to using plastic wads and copper jacketed pistol bullets. It might technically be a MLer, but its not the same experience. There is a lot of information here for anyone willing to read to find out how to be a fine marksman shooting any traditional side lock percussion or flintlock rifle or shotgun. There is just no excuse for cutting corners. You only endanger yourself, and the people around you. Last time I checked, there were very few people hunting with strangers. :hmm: