I have two different rifles that always throw the first shot from a clean barrel just a little bit off of where the others will hit. If I do not specifically fowl the barrel I get a first shot flyer. Some projectiles are not all that bad. Others are terrible. I have learned to combat the first shot flyer by fowling the barrel or as told by another poster I added a touch of bore butter to the end of the sabot of the first shot and that brought the group much more in line.

My Knight Wolverine will commonly throw the first shot almost an inch an a half to the right and at 2 o'clock. All the rest will be right on the money. With patched roundballs this is not so apparent. They do not seem to fly with the first shot as often although I have one ball rifle that will throw the first shot off a clean barrel.....