The Bear Facts!
Actually, I became the "default"problem bear man in a huge construction project in the northern Rocky Mountains in the late '70s and into 1981. There were numerous construction camps (Atco trailers) populated by, essentially, idiot construction workers who, in the late long summer evenings, would take a huge fudge brownie outside alongside their good old Kodak Instamatic "to git a pit'chur for momma back home" of a local grizz or blackie!"
After trying a Ruger .44 Mag carbine (bad idea), and watching the local game warden using his Win 88 in .308 (150 gr bullets) somewhat unsuccessfully, I eventually switched to a new Marlin 1895. I initially used the old Remington 405 gr light loads but soon enough changed to handloads using two bullets: Hornady's both. One was their 300gr hollowpoint, and the other was their 350 gr flat point. I did try to use a 500 gr from the .458 Win Mag but had to disassemble the lever to get the round in. As well, the recoil loosened the forearm, so that idea was "out".
i settled on two good stout handloads, not the absolute top end, but about 2000 fps for the 300 gr and 1850 for the 350s. Both worked fine, always extracted easily and any bear thus hit would at the very least sit down. Gave me a chance to exercise my well-learned maxim about bears: *NEVER SHOOT A BEAR JUST ONCE!*
Well, unless you are potting him as he munches contentedly on skunk cabbage at about 100 yards away, and he decisively falls over and never twitches again. But if he's less than 25 yds away, and is snorting, popping his jaws and lowering his ears, and casting evil aspersions in your general direction, you'd better get on with it. One into the lower chest, just to one side of his midline, so you "collect" some critical clockwork, and he'll go down. Then another one right into the head, and you're done. But stay alert; one of "her" cubbies might be around, or a following old boar. Yikes!
Friend of mine had one old boar pop his head into her cook tent in the Yukon and snarl at her. She politely stepped out the other end (always a good idea with a wall tent to have doors at both ends...), picked up her Marlin 1895 and dropped him with one round of her .450 Hornady Mag, into his head. Down he went. (she didn't follow my MAXIM rule tho', but fortunately it all turned out OK)
Other cartridges? Sure. Lots of choices, even a thutty-thutty [God help you...] but in the end, I had to dispatch 31 bears, including one polar and two grizz (I used to be a bear researcher in Canada and Alaska and over 10 years I found myself in a number of ticklish situations.) I learned a lot about aggressive bear behavior when they are ticked-off, which is far different than if you surprise them with a quick shot. Probably could do it with a .22LR if you got 'em right in the ear!
I worked on, and "saved" quite a few bears through my research, but every once in a while I'd come across a nasty, upset or aged bear. I later found out that the Marlin is THE most popular rifle in coastal Alaska, and why. The new stainless short-barreled large loop Marlin is a fabulous choice for a hard-core bear shooter. topped off with a red dot reflex sight, or a ghost ring peep, it's hard to beat. The Winchesters are grand, but not as strong, nor as fast or indestructible.
Since then, I've loaded quite a few good medium-hard cast flat "meplat" bullet loads in the 350 - 400 gr range, all at about 1850 fps. That will, trust me, do the trick @ <80 yards. Quite decisive.
BTW, handloads in the 45-70 are more reliable in feeding than the oddball 450 Hornady. Since they did that simply to prevent it from chambering on old 45-70s they also should have taken the opportunity to shorten the round by about 1/4", use an apropo powder and gain another round in the magazine. Then it could have also been used in some godforsaken handgun. Ouch!
On that score, BTW #2, I also carry a 8.75" FA .454 Casull which pretty much duplicates a 45-70 snugly resting out of the way on your hip, which suits it well for the tough Alaskan bush and those durned willows and alder "pickpocket" shrubs! I also had Freedom Arms make me up a totally flap-covered holster for the bush country. The FA revolvers are sorta too tightly-toleranced for that blowing river dust and sand; you've got to keep them clean up in that country.
Have fun, and don't forget my MAXiM*. (Too bad Timothy Treadwell didn't spend some time with me... his girlfriend Amy would still be alive... sigh)