Years ago a Hudson bay Trader was in an Inuit village to do business, the men were coming back from trapping when a large Grizzly came into the village. It made for a hut with a woman and child in the doorway, the womans husband was one of the returning hunters. He was about 20 yards away and threw up his springfield 30 06 and emptied the full clip into the bear, it turned and charged him ripping of his head and right arm before collapsing.
When they skinned it out all five rounds had gone through the heart area killing the bear, but not instantly enough to save his life which he gave for his family.
45-70 no way, 12g with slugs or even double ought buck every time and at least a five shell mag.
Even then could you realistically do what that guy did, he was a professional hunter, who had lived all his life in the wilds?
Take a Mace spray with you , leave the macho stuff to Hollywood and most of all remember you are in the wilds not the local park and keep your eyes and ears peeled, give them all the room they want. just my 02 worth
Better the man suspected of being a fool keep his mouth shut, than to open it and remove all doubt.