That raises a question. Can a black bear accelerate to 25 mph faster than you can draw and aim your revolver? To stop a charge my guess is a .44 mag or larger would be a better choice for likely imperfect marksmanship.
I wouldn't be surprised if the commonplace 200gr loads hit a bit lower. Mine shoots right on POA with 200gr ammo. You could also try the 165gr Hornady load.I bought a blued Taurus 431 3" last week, box and papers and a Desantis holster for $350. At the range it shot both factory and reloaded 240 grain ammo 4" high at 20 yards. (I like the gun, is there a load that will shoot to point of aim?)