My nephew lives in Alaska and loves it enough to spend his life there. I miss him but I know that the hunting opportunities are great. He hunts a lot with a bunch of natives and they all use the .223 Rem. He uses a .270 with 130 gr. at 3100 fps and all of his friends consider him crazy over-gunned. Another female friend works at a remote fly in only hunting camp and she says that the .300 Win. Mag. is the rifle shes hears about the most. She will be home in another month and I'll ask her a few more questions about calibers.

I agree. I'd take my 270. I personnally don't agree with the term overkill. If you take any game animal through a shoulder blade you can say good bye to most of the front end meat and it makes no difference if it's a 243 or a 338. If you can handle the recoil go big, if not get a smaller one and be a little more conservative with your shot distance. I use a 270 becaause I have had 10 years of success with it and don't see much benefit in switching. My max shot is about 200 yards so a 270 is all the gun I'll ever need for anything I'd be hunting

I’ve watched a many take Caribou with 270 with 130’s just as good as my 338 Win Mag. Caribou are like antelope, it doesn’t take much at all to put one down. Because I was always in Bear Country and around Green Horns, I carried my 338 Win Mag all the time. As for the largest cartridge, I wouldn’t go over the 338 Win Mag it really causes a lot of hamburger and grease upon impact. I knew a idiot used a 375 H&H who wounded a really nice Bull never to be found and knocked down three Cows with one shot. Didn’t punch his harvest ticket but because he turned himself in, he was only fined $100 and suspended for hunting the remainder of the season. 2 weeks after this he wanted me to take him north of the Yukon River to shoot 2 Caribou on my tag. I told him no way!

I would take a 30-06 as a min and a 300 Win Mag as a max.

I'm with Coop on this one. I would be taking some potent bear medicine if I were hunting in griz territory. If a guide had a big bore backup gun, a .270 or .30-06 or 7mm mag should be plenty. Bottom line is MOP!

I have quickly and efficiently killed caribou with 257 Ackley Improved, 280 Remington, 300 Win Mag, and 338 Win Mag. I have noticed many Inuits use 223 and 243 for everything.
Your first shot is your best one, use it wisely.

Interestingly, just as Clay says, I have often compared putting down caribou to putting down antelope. Without the long distance and animal speed of the latter.

I have always used either a .270, 7mm/08 or 30/06. Try to keep all your shots inside the ribcage. If you hit the shoulder even a .270 tears up some meat. I helped a pal that shot one badly with a .300 Win mag and it was quite a mess to clean up. They aren't hard to kill and often are in open country and fairly easy to stalk if they aren't moving fast. We often take them while also hunting sheep so any good shooting medium caliber would be fine.