Buck shot can be a devistating load, and would be a good choice to follow up a bruin after its been shot. Especially if that blood trail heads into dense undergrowth. But, buck shot wouldn't be my first choice for the 1st shot. I'd want a bullet that would have full potential for full penetration with an exit hole. Not too likely with buck shot.

With a baited hunt, you will probably shoot from an elevated position. Your entry hole will likely be high on the bears body. If you don't get an exit hole with lots of blood then tracking will be more difficult.