I do remember reading somewhere that even after it is cleaned, Pyrodex can still corrode the metal. I have a .50 caliber Hawken that suffered that fate after using Pyrodex and cleaning it as usual, i.e. hot soapy water and oil after drying with boiling water. I stay away from the stuff. I did run a test with Clear shot substitute and found it did not corrode after sitting uncleaned for a year. Now don't cringe, I tested it on the already ruined .50 cal. I mentioned earlier. Oyeboten is correct, BP is available by mail. If you don't want to buy a bunch, maybe you know folks around your area that would go in with you to cut shipping?