I agree about the Remington 150 grain Cor-Lokts. Keep the velocity a little below the speed of light...... Somewhere below 3000 fps and they will work fine.
I also agree that a .300 Mag isn’t a plinking rifle, so plink with something else. But, when sighting in the 300 for hunting use the load and bullet you plan to hunt with. A little practice never hurts either and it won’t cost you an arm and a leg shooting Cor-Lokts.
Those who beat their guns into plows, will plow for those who don't.-Thomas Jefferson