The big .338's (bigger than the win mag). I love my RUM thus far, though I havent shot anything with it yet (i did shoot a few with a .340 though). I think that they are the most versitile caliber for big game.There is nothing on this earth that walks on land that it cant harvest with a good bullet, It is one of the best long range performers in a light rifle, and it isnt too big to hunt whitetale with (OK, maybe a little big, but i like a little overkill). That and since I was a youg teen I have been somewhat obsessed with the .338 diameter bullet and lots of powder.