When I was stationed in AK, in the 70s, I was told by the wildlife folks and hunters that one should try for penetration on bears, rather than knockdown. I backpacked into some remote areas for recreational prospecting. With penetration in mind, I packed a Ruger BH with heavy cast loads, because a rifle was just too heavy for what else I was carrying. Never had to use it because I really tried to avoid tempting a bear into a confrontation.
I can remember three times that I had close encounters with them, in spite of being careful, and I told myself, "A rifle would be a good thing to have, here, now." Oh, well, you use what you bring. As I said a while back on this thread, if I were deliberately going after bear, I'd have the heaviest caliber rifle I could shoot well.
OTOH, the BLM folks, after losing some workers to bears, issued short-barreled 12-gauge pumps with slugs to their field workers. They practiced with them on the base ranges. Didn't sound like they were trying for penetration.
Does anyone still make those nasty, evil, armor-piercing, OMG-copkiller, cartridges that the Brady Bunch, et al, were crying about several years ago? Are they even legal any more? Would they be good for the penetration thing?