I live near cody. The wolves have completely destroyed this country. Rooster has a very good point on hunting rifles. You have got to decide what range you want to be effective at. If you want to go out beyond 650 or so yards get a big cannon 338. If your hunting is inside of 650 yards then the big cannon can be a liability and you are much better served with a shorter lighter easier handling rifle. I have them for all purposes. For elk I have a 338 Gibbs and a 338 winchester that do well out to 600 yards. They are light, easy handling and do not require a muzzle brake
. For long range elk I have several big 338's. The 338-378 gets the most work because of the superior velocity allowing me to use mil dots to longer ranges without using clicks whichs helps a lot when you must get on an animal quick. They are all very accurate. It weighs 10 3/4 pounds with a 28" Hart barrel and a mk 5 action. It shoots the 200 ballistic tip at 3600 fps, the 225 accubond at 3450, the 250 AB at 3300 and the 300 matchking almost 3100 fps. Those are the velocities maintaining excellent accuracy.
If you are building an elk rifle then build what is best for elk. Yes they will all kill elk with a well placed shot. But the 338 caliber is by far the best for long range elk and will give you the best odds for a kill. I would not even consider a smaller caliber if I were spending money for a rifle designed for elk hunting.