I've just been out with a new howa in 243 win. It groups within the inch with 3 shots but then I will go back to the rifle 10 mins later and fire another 3, same group size but off to the left by 2 inch and up 2 inch. I re zero and same happens. I'm using win xp 95 grain . Could this be caused by the barrel getting hot? Shot 40 in 2 hours with cleaning in between. I just can't get a constant group around the center.