Interesting stuff. My gun is overbore to be certain. The first bullet goes down the tube real easy and at the range the point of impact has been off by as much as 9 inches on a couple occasions. After that first shot, the gun then shoots great. Prints good consistent patterns. I have tried mumerous bullet combinations and they all have the similar effect in my gun. I can count on the first one to be a flier then I am good to go. I' ll take that dirty bore gun in the woods with me rust be damned. At least I know for certain where it hits.