Hang in there, you'll get it figured out sooner or later...ya might try some different shooting positions, a bipod, different kind of rest, sand bags, forend pressure, a pressure point on the forend...there's gotta be some combination that will get consistent shooting out of it.
I cut some pieces of refrigerator magnet and put em in my shooting box, they came in "handi" one day when shooting my mannlicher stocked 45-70, a pressure point was all that was needed on the forend, place the magnet in the forend just ahead of the screw and tighten the forend.
Good luck,
Tim