I remember the late Bruce Bannister [BruceB], telling me about a black bear that went for him at or around 25 feet. He told me he had no idea how fast he was working the old Enfield but happened to notice that there were 5 pieces of brass in the air at the same time. It really is knowing your gun.Get a good bolt gun and learn to run it. High power shooters used to say that bolt gunners didn’t like the AR because they didn’t like having to wait for the action to cycle.
I think a 358 Win would be about ideal. A 375 Win Marlin would be great too.
The 45s need bullet weight to retain downrange velocity. I chased that from here to there decades ago and realized that no matter what we do to the BC a 458 bullet drops like a rock from 100 and beyond unless we start it out fast enough that recoil is a killer.