Fish and Game had to take a 200 lb black bear on Ft. Rich (pre JBear) that had many .45 acp rounds, .38 spl, 5.56 and 7.62 in it, they stopped counting at 30+.
US Fish and Wildlife issues 12 ga with slugs (usually Brenneke), 45/70 and for those in Polar Bear or coastal Brown Bear country a .375 H&H if they can shoot it.
When I was with Dept of Interior we were allowed to carry .44 Mag, or .41 Mag handguns, 12 ga shotguns with slugs and 30/06 or above, most guys carried a handgun and long gun, being fairly young and in shape.
.338 Win Mag was popular because gun were cheaper than the .375 H&H and so was ammo.
300 grn .338 Win Mag, later used the 250 grn Nosler which left a large wound channel and penetrated well.
Fauna is getting more aggressive, moose, wolves and bear so situational awareness is really necessary.
If you don't know they are there you will be reacting to an attack, usually you loose.
Big bullets that penetrate are preferred but marksmanship is the number one requirement.
Take a truck tire, paint four inch white squares on the tread, roll it down a hill at twenty yards and see how many you can hit in 1.5 seconds...that is an actual bear attack not a bluff charge.
Bears, wolves and moose operate in thousands and hundreds of seconds, we humans work in tenths.