A few thoughts on Bears. I have taken Black and Brown Bear. In 95 I got a permit for Brown Bear in AK. It was when I saw my first big Brownie, that I began referring to Mister Bear.
There is a world of difference between hunting any Bear, and defending yourself against said Bear. It is true that if you wound a Bear, the Bear is going to be pissed off, and might even attack you. However most wouned Bear slink off into the woods and now it is your dangerous job to track and kill it ASAP.
It is when the Bear decides you are:
1. Good to eat and it is really hungry
2. A threat to itself or worse, it's cubs and it is going to eliminate that threat
Now is when your are going into Bear defense mode.
To kill a Bear at range you must hit a vital organ or organs and/or break major motive bones so the Bear is anchored.
To STOP a Bear when it has decided on 1 or 2 above you must make a central nervous system hit-read spine or brain hit. A bear with a broken shoulder can and will still kill you. You must shut down the CNS. Both the spine and brain are protected by masses of bone and muscle that must be penetrated by the projectile from either a shotgun or a rifle. One can see here that buckshot is out, it simply lacks the penetration except at point blank range, and when the Bear is at point blank range-so are you.
You will have to hit the relatively small brain pan, or narrow spinal area while said Bear is humping and swaying at about 30 MPH, or possibly a little faster, a motivated Bear can go over 35 MPH.
Obviously a heavy solid slug is needed, your call as to which. Mine is either a Winchester sabot round from a rifled SG barrel, or a heavy 45/70 like a 405 or 350 gr solid from Buffalo Bore or other botique ammo builder. I have a Ruger #1 in .458 Winchester that is also up to the job. The best bullet in the world is not going to hel you if it is not a CNS hit, remember I am writing about Bear defense, not hunting, although one can turn into the other rather quickly.
I suppose the 44 magnum handgun round would do the job with a heavy penetrating slug, ditto for the other big bore handgun with the proper load, but using a handgun might be a bit dicey when Mister Bear is pissed off.
ber are magnificant animals and I will not hunt them again, but I would not have missed the experience for the world, well, I might trade it iff for a real American President about now.