I Have heard thet carabiou are not hard to kill,but the range can be a little on the far side.Since moose are also on the menu I would go with the
300 Win Mag and a good 180gr Nosler Partion sighted in for 2 in High at a 100 and dead on @ 250 and about 7-8 inches low at 300 yds.
This should work good,also remember the rain gear.
BBJ

.300 Winchester Magnum hands down

YOU CAN'T GO wrong with any of those rifles. If you shoot the 300 well, it has a little edge at longer ranges. I have a 30-06 and therefore thats what I would use.

Nubo and I hang with different crowds. You hardly ever see a magnum in a moose camp where I hunt.

Most caribou are of a size similar to a mule deer. I'd be carrying either the .308 or the 30-06 for those animals.

I have a 308 Win in a Remington 700. I have shot 11 moose and some white tails and a bear, and only had 1 occasion with Nosler Partition amo when I didn't get a pass thru. Mabe a bad round? I dont know. As always the most important part is not the grain, caliber, of even game, it is shot placemant. Moose and Caribou are about 500lbs apart but for the most part they are slow moving animals that one can afford to pull off a accurate shot. Not even a Dinosuar can live with a pin hole thru the heart.

I would like to think that mine or another .338 would knock one down pretty good!

Shots at caribou can be longish, so I would pick the 300 Win Mag hands down. All will do the job of course in perfect situations, but since hunting is unpredictable, carry the biggest tool for the job. Use a 180gr. Fail Safe, or comparable bullet and you will not be disappointed. The Fail Safe is the deepest penetrating bullet on the market, and with moose penetration is critical. Good luck!