I have shot 15 plus turkeys with my bow. I have used mechanical, fixed blade broadheads and the gobbler guillotine. I have had the most success with the fixed blade. I try to shoot them when they are strutting I aim at the base of the tale. If you hunt with decoys face the decoys towards you because the turkey will almost always come up and face the decoy therfore his backside will be toward you. More times than not when I shoot a turkey like this I hit the heart.
I have had problems with the mechanicals not opening up and with the guillotine you will probably need longer arrows.