The only problem with most 45 acp ammo and bear skulls is the design of the bullet, being either a round nose fmj or a round nose/hp/soft point, and the sloped skull of the bear and the angle at which it is approaching you. Elmer Keith discovered, long ago, that round nose bullets (those from earlier 38-40, 44-40, 44 Spl and 45 Colt slugs is that they deform and follow the skull around and out rather than penetrating. He discovered this on bear and on cattle. His findings led him to design the semi-wadcutter slug with its sharp edged flat metplat and 'square' shoulder. Keith related a story about encountering a angry bull that he had to shoot - he was carrying a 1873 Colt in 38-40. His first round out was a factory load that failed to penetrate and followed the skull around until it exited the flesh - that round only angered the bull more, but his 2nd round into which he had loaded one of his swc slugs over a stiff powder charge penetrated stright into the skull and dropped the bull.
Years ago I tended to a man who had attempted suicide with a 38 snubbie and 158 gn rn bullets - he placed the muzzle against his temple and fired and the bullet traveled around his skull beneath his eyebrows (or just above them) and out the skin on the other temple. It looked as though he had shot himself clean through the head and survived but not so. The bullet had deformed and followed the bone, as round nose bullets tend to do. He had a massive headache but the day he got out of the psych ward he tried it again with a shotgun, and succeeded.....
The 45 acp, if loaded properly, will work. If loaded with a heavy weight (230 gns or more) swc, either hardcast or fmj, to about 950'/sec., you will get much better direct impact and penetration. I seriously doubt that most personal defense or police loads would work worth a darn due basically to the bullet nose design; none the less, I feel confident in black bear country with a 45 acp thus loaded with the swc slugs.
As regards the 7.62 Tok - I have been after a semi-wadcutter design slug for that bore for a while. There is one out there for some of the 32 caliber revovlers weighing in at about 98 gns and cast out to about .313-.314; possibly a closer to diameter mould and hardcast might drop it 10-15 gns to stay near the original bullet weight and a hardcast swc out to about 1400'/sec should be much more effective than any round nose design and should provide for better bone structure penetration. All this, of course, is just my two cents worth...........