Black bear, I would use anything I would for whitetail. 30/30, 45/70, etc. For Browns, kodiak and grizzly, depends on terrain. Not so close up shots, maybe an ‘06 but I have a couple 300 mags to choose from, so one of them possibly. If encounters will be much closer, 338win or 375h&h would be my go to. I would even use my 416 for good fun. Not because I feel it’s needed but because I’d want to