I have seen many articles and discussions about shot placement. What i cant seem to find is approximate average sizes of species hearts. Specifically Impala and Blesbok. Why would you need that you ask? I am taking my wife to Africa again and this time she will be hunting with me. She is a good shot but she is nervous about making the perfect shot. I have shown her the shot placement diagrams and she has seen Dr. Robertson's The Perfect Shot book but she cant seem to grasp the concept of the actual size of the vital triangle. I believe if she could read somewhere (she wont believe me) the size of the heart alone she would relax somewhat. She shoots sub moa for crying out load but never really hunts.