The Perfect Black Bear Cartridge??? I think it's found somewhere in the .35 caliber family.
.35 Remington in a 336 Marlin if you run Dogs or Doughnuts.
.35 Whelen in a Bolt action if you spot and stalk.
My choice...the .358 Winchester in a Boltgun, BLR,or a 99 as it is the best of both worlds.