I just asked a bowhunter from Zim. From what I can gather, a dead-centre rib hit stops the arrow in its tracks. The edges of the ribs, from one fellow's testing, allow the heavy, two-bladed arrow through. The most famous modern bowhunter, Chuck Adams, tried and failed. His elephant charged and was shot down by the PH. He shot the ribs after that, and came to the conclusion that it is wrong to hunt elephant with bow and arrow. A fellow might be able to arrive at a theoretical approximate percentage chance of success. The equipment he used seemed to be lighter in draw weight and arrow weight than what other successful elephant hunters use. As the Bible says, somewhere, "Let each man be convinced in his own mind." One chap says yes, one chap says no; anecdotal evidence for and against.

Regards,

Ben