A few more details might help pin point it. Onequestion is, does it do this for the first few shots from a clean barrel or always? I've seen many guns that will not shoot consistently until after 3 to 5 fouling shots. The most severe example I've seen was an older Win 70 in 270. The first shot out of a clean barrel was always about 8" left and 4" high at 100 yards and each shot walked back toward center and would be dead on starting around shot 5 or 6, then it would group into .75" all day long. That is the reason I will not clean my gun after my final sight in until after hunting season unless it gets wet or some other extenuating circumstances. Then I fire at least 3 fouling shots before going back out.

See if you can pin point a pattern and give us more details.