Ozy, what I tell my hunters and I tell them this way to make it as simple as possible, because when they get 18 yards from live buffalo, they are going to remember very very little. On a standing broadside buffalo, take a line straight up the center of the front leg and 1/3rd of the way up the body from the bottom of the chest. This will put the arrow in the center of a triangle, between the upper leg bone, the scapula(shoulder bone) and the thicker rib bones. It also puts the arrow at the top of the heart and into the lungs, really the ideal spot. The rib bones that lie beneath the shoulder muscle are less than half the thickness of those from the shoulder aft and they aren't so tight together. It is possible to shoot and arrow through the thickest part of the thickest ribs, I have done it, but it was with an 85# recurve and 970 grain arrows and a 160 Grizzly. And to give you and idea how big water buffalo are, that arrow is 33" long and on the broadside bull the arrow went in its full length until only the nock was visble and it didn't come out the other side!