I'm really glad we don't have the type of bears you folks have and report about. The black bears we deal with are exceedingly timid and always want to get away unless they're eating something. They have an incredible nose that pulls them like a tractor beam. They don't seem to have great vision but their sense of smell makes up for that deficiency. They can be surprisingly big.
There seem to be far more in and around town than in the backcountry. I used to spend countless hours suspending food while on backpacking and climbing trips but never saw one in the backcountry.
I've had them in the pickup bed after eating lunch there and leaving a banana peel. The biggest one I've seen was on my deck in the middle of the night the one time I left the barby out. My deck creaked when he was there and won't creak when I'm on it.
One walked into our camp once when we were relaxing. He walked around the end of a log we were backed up to. He was as surprised to see us as we were to see him. He bolted so fast his paws slid out.
I once came between a sow and two cubs while biking- the dreaded scenario feared by many. They left and I peddled by.
I don't think I could bring myself to shoot one so don't worry about best caliber. It would probably be a shot in the rear anyway.
I do look both ways when going out the door and don't leave trash or bird seed out.
Hope I haven't ruined my good luck here.