When shot well black bears die promptly

They do have large bones and can vary greatly in size so a big caliber can’t hurt

I would happily shoot one with a 6.5x54 in the vast majority of shots on bears that have been presented to me

I’ve killed them with the 270 win 130. I did put a second round into a bear with the 270 when it got up and lurched towards me upon recovery but that is a realistic but dramatic sounding recounting of something that was no big deal

I like to use the 338 wm, 225 or 250. On the unlikely chance a very large bear is encountered or a shot is taken at the shoulder blade it might help

Angry yelling aside in my limited experience and ample observation of old bush men from northern BC any rifle appropriate for deer will work for black bears and any sturdy elk load will take a grizzly easily with good shooting.