I too believe there's such a spot. I shot a buck with a rifle several years back that fell in his tracks only to get up and run off. I aimed a little high to compensate for the drop because of the distance however he wasn't quite as far as i thought so the bullet hit right where i aimed which was just below the spine but above the lungs. I found very little blood and looked for hours and several more hours the next day but still never found him. Made a believer out of me!