One of the loads you'll find in various manuals that works for me is 76 grains of H4350 under a 300 grain bullet. I currently use this powder {Short Cut version} but have also used IMR4350 and surplus IMR4350 at the same weights in the past. I have saved several 3-shot groups shot at 200 yards off the bench that measure under one inch center-to-center of the farthest shots with this load under the 300 grain Hornady RN. Of the 2,000 or so rounds I've shot from my SAKO .375 I am guessing 75% are this one load and I suspect it will continue to be so till the thing needs a new barrel.

It is the load I used in the bullet test thread and various velocities are shown there. Hovers from 2450-2500. Very low extreme spreads for multiple shots chrono'd.

It may be listed as max in some manuals so follow manual instructions for working up.