I have never put a bird (fowl) down a barrel, but I do fire a charge (foul) my rifle. LOL.

So, the statements above holds true if you load up on a clean barrel. However, if your gun shoots better with a fouled barrel, then I would shoot it at the end of the day, clean and reload. Lots of work! That is why I now use BH 209 in my guns it works in and 777 in those that don't. I have hunted up to 5 days with a fouled 777 barrel before I cleaned it and not had any problems.

Cleaning daily after each shot with real black powder seems to be the best course. One of the inconviences of using the real stuff.