Last year I started using xlc bullets in my 300 rum and they worked well. But this year when I rechecked my zero I couldn't hold a pattern under 3 inches and it has wondering can the xlc coating be apart of the problem?(nothing else seems to be wrong, scope mounts, ect...)I have never had this problem with other bullets (coated or other wise) I started use xlc for the reduced pressure. Any help will be appreciated.