If you sight the rifle in with a clean barrel, then hunt with a clean barrel. If you sight the rifle in on a fowled barrel then you might want to hunt that way. Many rifles will shoot very near the same POI on a clean or fowled barrel. We are talking just a small distance. Other rifles with certain projectiles will actually shoot a few inches different. These are the things that only practice at the range on a clean or fowled barrel will tell you.

On the inlines, I like to shoot a few 209's through the barrel before loading. Whether this would be considered fowling, I am not really sure. I suppose if the primers put enough crud into the barrel it would be. I then find that the difference between the clean and fowled barrel is very slight. My worst inline for difference in fowled and clean is my Knight Wolverine II. If you shoot on a unfowled barrel the scope is right on. If you do not at least swab the fowling out of the barrel, the shot will hit almost two inches in difference. I do understand this and keep this in mind when I shoot the rifle. I also practice with it both ways.

With my traditional rifles, they seem to shoot the same place whether fowled or clean, so I hunt them on a clean barrel. I also have made sure to practice and know where they shot will hit... Today I double checked the rifle at 100 yards. Both were within an inch and a half of each other. At 100 yards with open sights, I could not get too concerned with the difference. That could be a simple sight error on my part.