Well when I'm in bear country while hunting white tail, the "better options" for bear isn't going to be the better option for white tail.
Quite literally all of the better options for Whitetail are naturally going to be better options for bear defense as well when compared to 7.62x39.
Id only hunted the Black Bear with 7.62x39 for novelty, my hunting partner had a .300wm.
I was running Winchester SP in the SKS cus that was all i could find, shot like 4moa+ which was terrible even for the SKS IMO, but i knew my bear distance limit for the SKS was going to be <100m anyways.
Standing in a acre sized pocket of some of the thickest and most tangly bush ive ever been in... yearling Black Bear stood up 40m away from me. Only its face and neck were visable. I hadnt seen a single bear days prior so i decided to pull the trigger. Having never shot a Bear before, i did not aim for the face since i had read qbout bear skulls deflecting bullets (probably grizzly stuff, not black bear related lol) SO i aimed just below the jaw, figuring it would shred hos neck and severe the spine. POW! The bear dropped beneath the bush.... i heard thrashing and snorting.... and it was moving counterclockwise to my position. Next thing i know i hear this horrible scratching sound to my left, i instantly spin to face it and notice the bear has climbed about 20ft up a tree 40m away and is looking around all confused at the ground below. This time i have a much better shot. I put a round just below his arm pit. He releases and falls to the base of the tree with a ka-thump. Much to my surprise he gets up and starts briskly moving away. At this point being presented with only a juttering ball a black fur and me being fairly confused and desperate, i just aim center of mass and fire 2 rounds. One presumably hit, the other i later discovered hit a branch. The Bear disappears into the bush. I look down and the 5th round has actually hung up on the SKS's feed ramp (a common issue for many SKS rifles and lead tipped bullets). I clear the jam, and pop in a fresh mag. Then my partner yells from outside the bush patch "ITS HEADING EAST!" . I sprint in the direction hoping to clear the bush and get more shots off at the bear crossing the wheat field.... then i hear a KA-BOOM.. Plop. And my partner yells "I GOT HIM" . The bear had appearently stopped to look over its shoulder at its pursuers and was met with a single .300wm bullet. The Bear appearently dropped instantly and did the death thrash for a dozen seconds.
We skinned the bear at that spot and noticed only 1 bullet wound.... the .300wm. This troubled me deeply, so i walked back into the bush and retrace the events and the bears path. I naturally started at the point where i believed the bear was standing while looking at me. I look down at the mossy forest floor and instantly notice a cups worth of blood spilled. I got that sinking feeling as i realized that i did infact hit something. Then i quickly came to the realization that there must have been TWO yearlings and i was on a blood trail with NO GUN. I exited the bush, went to the truck and grabbed my back up gun. A Fabarm STF loaded with 3" magnum slugs. Unlike the SKS I had COMPLETE faith in this gun. Once it was in my hands i felt pretty confident following the blood trail. I didnt go much further past the tree that the bear had climbed before i noticed a dark figure buried in the depth of the bush. It was the wounded bear, sitting there, starring at me not 30m away. I put a slug between its eyes and the pain and suffering of that poor bear was finally over. It was riddled with bullet wounds qnd had lost a ton of blood. It was probably minutes away from slipping away. But nonetheless i was NOT IMPRESSED with the wound channels created by the SKS. It was like i was shooting FMJs.
Never had a reason to hunt black bear after that, but I still hunt plenty of deer and small game. Using my 7.62x39 guns to shoot plenty of porcupines and coyotes... often with Ukrainian HPs, i noticed the wound channels created by those was always decent, and the kills completely ethical. So one year I secured a box of Hornady SST 7.62x39 rounds. And i decided to shoot a Whitetail buck with it. 120m broadside shot to the "boiler room" area and the Hornady SST round did EXACTLY what ud expect a good expanding round to do. The wound channel looked really no different then something a .243 or similar cartridge would make. Been using it ever since. With exception to last year where i couldnt find any once again... so i used Western Munitions 150gr SPs. That round appeared to expand well but not as much as the SST.
Armed with SST rounds i wouldnt hesitate to shoot a Black Bear. But 7.62x39 still wouldnt be my first choice... or even my 3rd lol. Only novelty would compel me to do so. And after the shameful suffering that bear went thru I now put A LOT more thought and consideration into how novel i decide to make my hunts.