Personally I wouldn't hunt anywhere there's a chance of running across the "GRIZ" with anything less then a 300 Remington Ultra Mag. And Brown Bears and Kodiak Bears are even bigger! Its a safety issue! Can you kill a big bear with a 30-06, you bet you can. You can also go to the dentist and have a tooth pulled without using Novocain, it just ain't the preferred way of doing it! The 300 RUM using 180 gr. bullet is getting 4200 ft. lbs. of energy at the muzzle and 3200 at 200 yards. I wouldn't use this cartridge to hunt big bears, I would use the cartridge to hunt where there are big bears. If I were to hunt any of the big bears I would pick the 338 Win Mag. as a minimum. It may not have the "hot ballistics" on paper that the 300 RUM has. But it has a really good selection of bullets that are made for "heavier game".

If your going to stay out of "bear country" then anything from a 308 Win., 270 Win., 280 Rem., 7mm Rem. Mag., 7mm RUM, 30-06, 300 Win. Mag., any of the Winchester WSM's will work just fine. So will some of the Weatherby cartridges such as the 270, 7mm, 300 Weatherby Mags.