RE: Cartridge Choice
First off, what do you mean by big bore? Big bore means something completely different than the calibers you described. When guys use the term big bore they are usually talking about .375 and above.
What makes you think the 30/06 is a slouch? Really, hundreds of the animals you stated have been taken by the '06 at ranges further than most guys would want to shoot. But, aside from the 30/06 any of the .300 mags are great choicesand they give a great mix of energy and velocity. Makingthem an elk hunters dream.Imagine a flat shooting 180 gr bullet hitting with almost a ton of energy at 400 yards. That's why they are so popular amongst big game hunters.
Any 30 caliber that shoots a 180 gr bullet at 3000 fps is going to hit hard!