if you want a gun for everything i tihnk a marlin 45-70 is your gun. for bear hunting or defense Garret makes Hammerhead cartridges that throw i think its a 500 or 550gr bullet at 1500fps, which is definatly good enough to take any animal in the world, so thats what id pick. if its got to take a beating a scoped rifle may not be a good choice at all due tot he optics but at the distances you mentioned then peep sights on at 45-70 will work magnificently

propmahn
save the world, reload your brass