Fred Bear killed an elephant with a bow and arrow, probably not the smartest thing to try and certainly not what I would choose to use, if I wanted to kill an elephant.
There is no answer to your question, it all depends on what you are willing to put up with. Quick sure kills or the possibility of wounding an animal and it crawling off to die.
The possibility of making a bad shot is always there, but the probability can be eliminated, to a certain degree.
