James, I've never hunted bear in a serious way. Friend and I used to go up into the N GA mountians hoping for a chance at a blackie.....
Anyway, I'm not convinced that bear are as terribly dangerous as folks say. You ain't gonna go messin with a cub or a den, you ain't going to try taking a salmon away from one....
It is interesting that in John Brownings biography, the last bear hunt he went on is described. He was using one of the first single shots he made, the owner had abused it and he was concerned about the rifle extracting from the rusty chamber, he took a rod with him to clear such a failure. He perched himself on a ledge and shortly a bear came out on a ledge below him, and proceeded t watch the sun set. Browning watched the bear watching the sunset, never fired. Browning says never hunted bear after that.
My dad spent his college years in Idaho after WW2. We have family in Wyoming, he spent the summers working on their ranch. A hand on the ranch that dad stayed with and helped as he was dying from cancer told him that the best way to kill grizzly was either with a bow or with a log trap. Bear couldn't hear the direction an arrow came from and couldn't return the attack. The log trap was a ham tied on a small log, in a stack of logs designed to collapse when the ham was pulled on. I don't doubt that bears can be dangerous, I just wonder if the myth is greater than the reality.
I have little trouble loading Handi quickly. Could I beat a charge from 20 yards? NO. But I don't thing anything other than a auto would help in that situation. I have little trouble having a second round in the chanber when I've shot a deer, and quickly enough that I have been able to put a second shot on one before it traveled 10 yards. A little practice and it loads as quickly as removing a lever from your shoulder to shuck the action (not the right way for those who may not know) Practice, stick a cartridge or two between the fingers of your left hand (assuming right handed) fire, press the action lever,let the spent case fly, stick in a new one and shoulder it up. A good low power scope or simple open sights. Not even irons. Shallow folding V's were the item of choice on double rifles of African dangerous game, that may be the best choice. Would I use a single on DG? probably not, but I don't find it a terrible handicap. Be sure your first shot breaks the shoulder, it is hard to charge when you can't get up off the ground.