Whelen, if you are using black powder, try to wipe the bore after every shot, as Mark mentioned. If you are using Pyrodex, the manufacturer recommends NOT wiping between shots, and I don' t find it necessary to do so. Some of the other substitutes will allow several shots between wipings also, but I found that is not true with Triple 7! I had to wipe after every shot with T7. A buildup of fouiling can prevent you from getting the ball all the way down onto the powder charge, then you are in trouble! The ball has to be seated firmly against the powder, or the gun could be damaged when the shot is fired. If you can' t get it down, it will have to be pulled, or the breechplug will have to be taken out so the charge can be safely removed.
Always clean your gun thoroughly after any shooting when you are finished for the day, regardless of what kind of powder you use!!