Re: first groups out of new rifle
I would personally lean more towards something binding or touching as the barrel heats up. It would be hard for me to imagine that the seating depth of your rounds would cause what your seeing. If this were the case, how would you not see different rounds being the flyers, or just happen to pick up the "different" rounds, on the third and sixth shot?
Possibly there might be just a tad of something binding in the bedding around the recoil lug or the back screw on the action.
Overall to me it just sounds like a heat induced or realted symtom than anything else.
Let us know if you find the culprit.
At worst, your hunt should not be to much of an issue, as the first two shots are spot on, so yoiur elk should be on the ground before you have to worry about the drifter.
Mike / Tx
"Heck why would I lie, most folks don't believe the truth when I tell them"