Lots of clients from the lower 48 ask me about gun selection for bou and I always tell them to bring up the rifle they are most comfortable. Too many come up with cannons thinking caribou are thick bodied animals. I have taken them with .243, 270, 30.06 and .308. For just joy of hunting caribou the .243 is my favorite because it can really reach out there and bring them down at long distances and very little wasted meat. 1 shot and 1 kill.