What makes you think BH209 fouling is not corrosive? It certainly is corrosive just not nearly as bad as most subs AND it should be cleaned with a oil based solvent not water based.
http://www.blackhorn209.com/specs/general-cleaning/
http://www.blackhorn209.com/faqs/
Use ONLY oil-based solvents. DO NOT use black powder cleaners that are water-based.
Thats gunna get rather pricey flushing a can with a solvent plus other issues that might occur from not being able to dry it easily. Would you just "rinse" your barrel out and call it good to go?...Somehow i doubt it. You would want to at least run a patch or brush to remove it.