i caribou hunted a few years ago with Jack Hume Adventures in northern Quebec. I had a great time and could answer any questions about the outfitter if anyone is interested. My main point was to say that I took 2, 20 round boxes with me, and returned with 37 shells, two caribou, and one "sight-in". I took my .300 Win Mag in a Stainless Model 700. My advice is this: take something stainless if you have it, it rained/sleeted/snowed part or all of my 6 hunting days. I only saw the sun for about 10 hours total; the other piece of advice is to take a caliber that you can shoot well. The shots can be long, and caribou are not tough. I would say anything above the .243 would be fine, just as long as you are comfortable with shooting it. Be prepared for the weather and shoot anything that would kill a large whitetail and you'll be ready.