There are several calibres around the north. Inuit near the tundra have to deal with grizzlies which are more aggressive then most polar bears. Some guides carry magnum cartridges for them but hunt with .223/.243. More north you’ll see mostly rim fires and old British rifles of the .303 caliber or older.308. If their in the Canadian rangers ( not necessarily indigenous ) their carrying the new “tikka” arctic 308 (assembled by colt Canada I believe) it’s laminated wood has Canadian red plys. The civilian model is an orangish colour. I think the sights are a bit different too.My friend killed his first deer with a .22 long rifle when he was 7. He never hunted deer or elk with anything bigger than a .243. But, he can shoot. I read once that the Eskimos hunt mostly with a .223. The big gun they bring out when hunting polar bear, is a .243. I know that we Americans have magnumitis. Partly because we can, and partly because we want to. I know the rifle I shoot best offhand is my 7mm TCU. It is a joy to shoot, even in a 5 lb. carbine.
As someone else pointed out, bullets today are so much better than 30 years ago. But, picking the right bullet is important. I shot a javelina with a 10" Contender in 7mm TCU with a rifle bullet, and it went right through and the javelina kept going until I put one through the shoulder. Once I switched to a Speer varmit bullet with a huge hollowpoint, they dropped in their tracks. I believe there is a sweet spot between recoil, b.c., and sectional density. For me, it is a 168 gr. 7mm going around 2850 fps. To each his own.
For knocking over deer, I've never shot a centerfire that drops them like a .45 caliber 340 gr. muzzleloader bullet.
You should see what it will do with the 69 grain absolute hammer at 3800 fps it is wicked on deer and hogsI think the 243 with the modern monos - 100 Cayuga, 100 Badlands BD-2, or 101 Hammer would do excellent on deer-sized game and give you more shot angle opportunities. If you have enough twist to run them, which many factory rifle barrels do not.