The old buffalo hunters of many years ago had nothing near as powerful as you talk about using. They killed hundreds of buff from one "stand" without moving. They sure didn't have .338 power. I think that nearly any factory ammo for the .338 that shoots well in YOUR gun will do just fine. If you are a handloader, the 210 and 225 gr. should give you all and more than you need, driven at respectable velocities, provided they give you rasonable accuracy also. I really feel that your needs will be met with the bullet weights normally accepted for .338 usage----i.e........much less than what you originally questioned.......