I've killed three black bears (two were 6-footers) using my 9.3 x 62. As handloaded it's easily the equal of a .338 Win Mag in KE with higher momentum and wider bullets. The last 2 were killed from single shots from 68 to 85 yards - one with a 286 Partition at +2600 fps and the last from a 250gr AB at 2700 fps. They both went about 20 - 25 yds. They were not CNS hits. So, the 9.3 x 62 (nor .338 Win, nor .375 H&H) are stoppers unless it's a CNS hit. In sharp contrast, the .45-70 IS if the right bullet is used (400gr at 2000 - 2100 fps) even without a CNS hit. That's why for my bear hunt this spring, I'll be toting my Ruger No.1 in .458 Win Mag firing the Federal 400gr TBBC at 2250 fps - a first for me in ever using factory ammo in any .458 Win Mag or .45-70.
As it's been pointed out by a few on this thread, according to the OP's criteria, this topic has/had reference to an "in your face" encounter - not a chance for multiple shots! One shot and whatever happens, happens. I've written much about this in my blogs. A stopping RIFLE, not one that is loaded with +3 - 5 is going to save the day and a life!
Full penetration from a .338 cal may be the same as a .458 but there's a HUGE difference in the size of the wound channel! How do I know - just ask me!
Bob
www.bigbores.ca
