I was always of the opinion that if I lived up north, I would carry a Glock 20 (10mm) with high speed 180 gr bullets. Those come out as I recall at about 1,400 ft/s.
But I do not believe that northern bear would be stopped with any handgun ammunition, unless the skull was penetrated. I still think that the animal would do sufficient damage before it bled to death.
When I lived in Canada, I shot a medium sized brown bear with 30/06 at about 150 yards. Bullet tore through the lungs and riped out big chunk of the right shoulder blade. The bear still ran up a tree that was 200 yards away and stuck 30 feet high. I had to get him down with another shot through the lungs - and he STILL hung there - for about 20 seconds.
Hence, I would surmise, that effective shot placement is the key. Since most handgun ammo will just bounce of the bears skull, I would opine to say that the 5.7x28 197 aimed at the head would do the job (penetrate).
Aside from that, the gun has very little recoil and hence subsequent shots can be made easier and more accurately than those of the .44 magnum variety.
But to get that head shot when the animal is running at you at 45 mph with his head bobbing all over the place is going to be a tall order no matter what gun you have.
Bring a REALLY big knife as a backup :-D
... keep on target ... keep on target ...
-TH