ORIGINAL: Todd1700
First have you patterned your shotgun aiming it at a very large sheet of poster paper? The reason I ask is that many, many, shotguns do not throw the center of their patterns to the exact point of aim ofthe front sight. In fact I have seen some that shot as much as 6 or 7 inchs off at 30 yards. Easily enough to make you miss a turkeys head. The addition of an adjustable sight can correct the problem if it exists. Also a set of front and rear fiber optic sights will make you keep your head down when aiming. Liftingof the headbeing a common reason for missing as well.
Check out Swampcollie's sticky about patterning your turkey gun. He explains the need for a large target vs. an 8 1/2" x 11" target with a turkey head on it. It's amazing what you find when you can see the whole picture. When you only use a front bead it's easy to miss a bird, even at 40 yards.