I’d like to weigh in here on this gun and this specific issue... powder and cleaning. I felt the same way as Bigslug prior to joining the North-South Skirmish Association. Now two things have changed. First, I won’t use anything but actual black powder rather than any BP substitutes, all of which are just as likely to cause fouling and corrosion with insufficient cleaning. Second, cleaning after shooting BP is actually pretty easy, especially with a single shot like the Ballard. A mix of soap and water or one of the mixtures of soaps and alcohol (I favor a mix of isopropyl, peroxide and Murphy’s Oil Soap in equal proportions) repeated a day or two later and followed by a good oiling and you should never have a problem.
Finally, a comment on the chambering... the 40-65 is a sort of modernized update on the old BP cartridges of a century plus ago. It has been designed and tested to be good for modern BP games like Silhouette, and that’s what I would plan to use it for. Others, not so much. JMHO, YMMV!
Froggie