Black powder got hard to come by and Pyrodex was just about all there was so I shot a lot of it. Accurate loads with plenty of power. Cleaning well it seemed to me Pyrodex does cause rust quicker than Black does. However I never noticed it to cause rust after I cleaned the rifle and oiled it properly. I like Shooters World MPB much better presently and recommend it. Rust is hardly an issure, easy to clean. Power level is adequate and I have found it easy to get good shooting loads.