Here's a link showing the preferred shot placements with different angles of a turkey. When body shot, most turkeys won't drop on the spot. The head shot is king at dropping them in thier tracks every time. If you killed the two birds that you shot this spring, then you did just fine with your shot placements. If you want to drop them in thier tracks, the guillotines with 4" cut put to the head/neck is the way to go. Not for everyone and not necassary to kill a turkey.
http://www.huntingnet.com/forum/tm.aspx?m=2071661