I've heard that it's ok but I'm no expert on brown bears or polar bears so I defer to the people who are on such things. But I am sure they will do the job on black bears. That's good enough for me. If I was going to brown bear country I might think about carrying a 300 gr. BB cartridge just in case. One shot is usually all you will get anyway and I think my Smith might survive one shot with a bigger load. But shooting it on a regular basis with those loads is totally asking for problems.