I would use the WW balls - straight WW - no need for quenching. At Brinel 10 to 13, they will be fine. Quench if you want, I'm sure it is not necessary. They are not that sturdily built. Muscle - absolutely, but light of bone for their size.

I put a 14 bore WW ball through a bull moose's leg - high up and it was barely deformed - not riveted at all - close to 3" in diameter.

The moose's bones are much thicker and harder than any bear's leg bones.

Grizzies have bones like a moose calf - about 2" or less in diameter. Ribs like deer ribs - at least the grizzly carcass we found exemplified how lightly boned they are. Thick & muscular, but lack of bone mass.