I need to ask a question of all you guys?
How are you cleaning your MLs? You shouldn't be using any petroleum based products in them. The petroleum breaks down and gums up with black powder or a bp substitute.
All my Mls (even my in-line) are cleaned with hot soapy water, hot clean water flush, bp solvent such as Butch's of T/C #13 and then the bore coated with Natural Lube / bore butter.
I never have excessive fouling. I do clean the bore at the range with bp solvent after every 3rd shot if I'm trying out a new bullet. This is only for accuracy reasons.
If I'm just playing, I just keep on loading and shooting. Maybe running a brass brush down the barrel about every 5th shot or so.
I will try that alcohol/windex solution though. It sounds like it would work well.