I shoot a T/C Black Diamond. The last two times I have sighted-in, my first shot (clean barrell) has been about 4" high at 100 yds. However, my 2nd, 3rd, 4th etc shots are consistently much better. Does this have anything to do because the barrel is now dirty? Also, should I be concerned when firing at a deer with that first "clean" shot?

Thanks.....Jimmy