I'm still seriously confused. I didn't comment on your other post because I have absolutely NO clue as to what your problem could be. My confusion stems from your precise description, it being 18" off first shot from a COLD barrel being fouled or not.
What Justin said may clear it up a bit in my brain but I'm still having a hard time figuring it out. Maybe with the heat expansion the burr doesn't effect it. Have you tried a hundred or so swipes down the barrel with some JB bore paste? That stuff works wonders!