i've been to the range 3 times in the last 12 days with my encore in .25/06. while my groups are 1" or less, they are continuing to move up. for instance back on dec.1 i had a load hitting 2" high at 100yds. i went back on dec.8 and the group was hitting 3" high. today i went and shot and it is 4" high. all my rings and bases are tight. any suggestions?