Here is a lot better explanation of shot placement. I took this off the AT site again. I hope this clears things up somewhat. I like how this explains the "boiler house."
My aiming point is not so much where I want the arrow to enter or exit but where I want the arrow to bisect the the deer's chest cavity. If you put a vertical line directly down through the center of a deer, even with the back side of the deers front legs, then bisected that with a horizontal line just above 1/3 of the way up from the bottom of the deers chest. This is the "geographical center" of the deer's "boiler house". This point is just above the heart and through the center of the lung area. If you look at a 3d model of a deer, such as a 3d target, and practice imagining where this center point is from different directions you will see where you need to aim to get your arrow to bisect this area. A low hit from this point puts you in the heart with at least one lung, depending on the severity of the angle. A left or right miss is still in the lungs as is a high miss. A direct hit takes out both lungs and the arteries coming off the top of the heart. Severing these arteries, I believe, leads to a quicker recovery than a pure heart shot. When these arteries are severed the deers blood pressure drops immediately to 0 and it quickly loses consciousness, while it's heart continues to pump, making for a better blood trail. While a shot through the top portion of the heart results in the same thing, the bottom of the heart is primarily muscle mass and cutting through this results in a deer that can stay on its feet much longer. Also, aiming directly at the heart and missing low will get you only brisket and a tallowed up arrow.
When I'm drawing on a deer, I'm not concentrating on an exterior aiming point, but rather concentrating on the "geographical center" of the "boiler house". Along with picturing your aming point, regardless of the method you use, you must exercise restraint and wait for the proper shot angle. A "quartering toward" risks hitting heavy bone and limited penetration or getting only one lung and an exit from the paunch that leaves little or no blood trail. The same goes for a deer that is quartering sharply away. In order to get into the "boiler house' from this angle the arrow needs to enter behind the liver and diaphragm, again limited blood trail, and penetrate much farther in order to give you an exit wound for easy trailing. Too many of the "I can't find my deer" threads on here are the result of poor shot choices. If you hit an unseen twig or just make a bad shot that is one thing, we all have it happen, we're human. But to take risky shot angles is the result of poor planning or decision making. Sorry I got long winded, just had a lot of stuff to say on this topic.
