I would take that 42.5 grain load and play withe seating depth. Maybe start at the lands, and back it up 5 or 10 thousandths at a time shooting 3 shot groups. Somewhere in there you will have a depth that will make a better group. Mine usually ends up being somewhere between 15 and 35 thousandths off the lands....probably no rhyme or reason for that, it just ends up that way alot for me.