Thinair is right about the .280 AI being a good elk and sheep round. And you can fire .280 Remington ammo in it on those trips when the Airlines loose your ammunition. All it does is give you a little lower velocity and fire form your brass for you. It is a very good round with the heavier (175 and 180 grain) bullets without the heavy recoil of a magnum. Reloading it is easy, and brass can be bought or made easily. I just like the .30's because of the larger hole they make at distance. I know (I live in Colorado) what is the minimum caliber allowed here, and I know some very good hunters who have killed elk with the .243 (I have a 6mm Rem). I wouldn't take a shot with a 100 grain 243 bullet on elk at anything over 150 yards, if then. I want the weight and mass of a 7mm or above heavy bullet. I want the inertia, and the tendency not to deflect off of bone. I want an exit wound and a good trail, in case the animal doesn't drop right there, and I want to be able to break large, heavy bones at whatever distance I might get a shot I know I can make. I use a .35 Whelen and Speer 250 grain or Sierra 225 grain bullets, either of which are devastating at 600 yards. At 8,000 ft they shoot as flat as a 180 grain 30-06, but hit with around 1,000ftlbs more force, and a lot more mass. Last year, my friend, George went Antelope hunting with me and shot a doe with his 6.5 Creedmoor at about 150 yards with a 140 grain ELDX, if I remember correctly. I watched the impact through my scope, and it was a beautiful shot. We trailed the antelope for about 800 yards but couldn't get another shot before she got onto someone's land where we didn't have permission to go. I have shot three antelope in the last two years with either a 30-06 or a 300 winmag. Ranges have been 80 yards to about 350 yards. All have been on the ground with straight line exit wounds ranging from 2.5 inches down to about 1.5 inches. So yes, bigger is better. The .280 is a good idea, and would be a great Sheep, mountain goat and elk rifle. So would a 30-06 AI.