I have been hiking in PA black bear country for over 50 years. I have encountered many black bears without incident. I have experienced 2 defensive charges from females with cubs. A bit of bear spray ended those capers. Te scary incident was a big male who made an aggressive charge. First shot of bear spray turned him away, but he came back. Second shot of bear spray drove him off. He did not come back. Bear spray is better than a gun, which should be the alternative if the spray does nor end the incident.
I have studied a great deal about black bear encounters over the decades. First advice is do not shoot for the head of a charging bear. Very thick skull can cause ricochet and failure to stop. Bears run at 35 mph. They can close 50 feet in a couple seconds even with a bad headache. Bear spray repels them or slows them down. Move to side for a shot to the side of the head or even better to the torso right behind the shoulder. That's where the hear and lungs are.
In the woods I carry Underwood Extreme Penetrator +PP 9mm. Do not use JHP. Penetration is the key. A 357 with that ammo ought to be ok for a black bear. In CO you might encounter black or brown bears. If I were going there I would want a 45 magnum. But I am not going there. In CO you also have to be aware of cougars.
Learn about the difference between a defensive and aggressive charge. The bear will actually let you know whic. A defensive charge come with a lot of growling, standing, and showing teeth and claws. An aggressive charge the bear get closer to the ground, does not stand in 2 legs, does not growl, has ears pinned back and eyes always on you. It's damn scary. Read up,on bear spray — it's your best first line of defense. Good luck.
Added later. Forgot two things 1) if you have to shoot the bear keet firing until it drops and be prepared in case it gets back up. The problem with a revolver against a bear is capacity. The the Adrenalin rush you will not be achieving range shooting accuracy. Today when I go into bear country I carry 15+1 with 15 more in an OWB mag pouch.