I havent shot any but try from time to time...but I know you shoudl aim at the butt of the wing...OR the actual butt if he is facng away with fan up...shoot right for the hole.
Im no expert, but i have killed four with a bow in the past two seasons. I have read a lot about it and studied the anatomy of a turkey a little too. The best thing i can figure and it has worked for me is use as big of an expandable cutting broadhead as you can. I use a Rocket Tom-O-Hawk 150gr 3 1/2"cut. Shoot for the butt of the wing (the softball sized area where teh wing connects.) Aim High as a turkey's vitals are a little higher than a deer's. I hit one two years ago low and back and he flew 150 yards, lit in a pine tree, and sat there for 30 minutes before falling out dead. The others i have taken their wing out and they havent gone more than 50 yards.