There was an old 2010 topic about what pistol caliber is enough for bears in this same sub forum. Although that topic was more slanted towards what pistol to wear while bow hunting in bear country, it's also an intriguing topic for hikers, people scouting, riding horseback, bicycles into rough country and those of us who are gutting an animal when rifle hunting and our rifle is leaning against a tree, etc.
With that said, I'll open the ball with the info and link below. What do you think, agree with or don't agree with? No real wrong answers as each of us is going to have an opinion about what level of chance we're willing to take or not. Personally, I like the 44 Mag stats for any bear but would feel comfortable with a 41 mag or 10mm for black bears.
Below quoted stats from article at the link at the bottom.
Dean Weingarten wrote a comprehensive article at Ammoland.com about real world pistol encounters with different kinds of bears and the results. I know we all have our preferences and comfort zones but some of the results might surprise you. I'm writing a summary by caliber but strongly encourage anybody interested to follow the link below and read the individual accounts. Some were black bears, some grizzly and some were brown bears.
9mm--4 cases, all successfully stopped the attacks.
.357 Mag--3 cases. 2 were successful, 1 was not.
.40 caliber--3 cases. All were successful.
10mm--1 cases. It was successful.
41 Mag--2 cases. Both were successful.
44 Mag--12 cases. All were successful.
45 caliber--4 cases. All were successful.
45 Super Pistol--1 case. It was successful.
454 Casull--1 case. It was successful.
https://www.ammoland.com/2018/02/def...#axzz7EDZwk600