You've been given some good advice. Definitely try some different bullets and powders. I've had good success with IMR 4831 and 7828. H4831 has worked pretty well too. The 150 gr. Nosler ballistic tip has been superbly accurate in my rifle and so has the 140 gr. Barnes TSX. Currently I'm loading the 160 gr. Nosler Accubond and it shows promise too.

If I were you I would NOT seat the bullets out to where they jam into the rifling when you chamber a round. You need to measure the actual distance to the rifling and then seat the bullet at least .010" less and really, .030" would be my preference.To measure the distance to the rifling take a fired case and very lightly squeeze the neck with a pair of pliers, just enough to lightly hold a bullet in place.Now, takea bullet and place it into the empty caseabout 1/8" or so and then chamber this round. As you chamber it, the bullet will contact the rifling and will be pushed back into the case.Carefully extract it and then measure the length. This will be the OAL to the lands.Take another 8 or 10 bullets from the same exact batch and do the same thing with them. After you've measured the length of these dummy rounds you can arrive at an average, which will be a more reliablefigure than just measuring one or two.Subtract .030" or so from that figure and this will give you the OAL you should start with. If you're using Barnes bullets you need to subtract .050". Keep in mind that any time you change bullets you'll need to recalculate the OAL since different types of bullets will not measure the same distance to the lands.