I've found B209(and/or the CCIM primer) still leave some residue around. Though this fouling is easier to deal with than that of Pryodex or 777. The best part is you can set your gun aside for a day or 2 on a hunt & not worry about it after shooting. A hunt is usually a few shot or less event. If shooting a bunch at the range I would plan to clean that day. I have had no problems going several(5+) shots over a few days & not cleaning, not even a patch through. After this it still cleans up fine with Hoppes #9. I think I'll get another jug of B209 next time I see it near $30.
I have also done the Gen II Lehigh BP conversion on my Knight. My limited testing with it has shown a much cleaner area behind the primer.
Rebal, This Lehigh conversion is very specific for certain Knight M-Ls. There may be something for a CVA, but I don't know. I would clean out your BP hole well with a 'welding tip cleaner' or something similar. I don't fire primers only for any reason, besides limited testing. I just start off bone dry when gearing up for a hunt. If you have BP issues with your CVA the guys at modernmuzzleloader.com may have some tips.