RE: Which Caliber?
Most Definitely the 8mm Mauser!
I have shot Black Bear, Elk, as well as deer types. When hit they drop like a ton of bricks. You can forget Am. ammo. it' s loaded down to 30-30 power. Reload or purchase European ammo that hits harder than a 30-06. It' s not the speed of the bullet but, the hunter behind the firearm.
John