On the side view of a strutting tom, you aim for the wing butt (where the wing attaches to the bird) or slightly behind it. IF you take out the wings, he can't fly. Slightly behind the wing butt is where the vitals are, like mentioned above, straight up the legs, above the drumstick. This is where I shot my first KS bird and he couldn't fly, expired in under 40 yards. The second bird I shot was walking away, standing upright, obviously you need to aim about center up his body from the back, I was lucky and took out the heart on that bird, he didn't go 30 yards.

Here's the link to a very good anatomy pic that Jeff mentioned on Mathews site. http://forums.mathewsinc.com/viewtopic.php?t=34266