I have a Benelli M2 with a Tru Glo Magnum Gobble Dot open sight, which I am going to replace with a Venom Red dot on a Sumtoy mount. Can I use the Tru Glo open sight to initially zero the red dot sight, by setting the red dot on the front sight?
Shoot 50 foot with a dove load. Draw you a 2 inch square and shoot at it. Then Put the dot back on the square and adjust/move dot to the hole or pattern. That should bring the pattern back to the square. You can go to 40 yards and try your turkey load then.
Sumtoys advice is sound.
If its on a gun i can i will look down the barrel at 50 yards and try and get a new sight in the ballpark.
I found at least in my house :). We always have a good supply of left over from the year before Christmas wrapping paper. It makes a great target backing turned inside out. I have a big piece of cardboard i tape the 4 corners then a dot or target in the center. This way i'm not going to miss lol and i can shoot a little farther for the first shot.
Off topic a little after i bore sight a rifle i use the wrapping paper and go straight to 100yds with my first shot.
A led sled is handy you can strap the shotgun down shoot. Set it back up with the red dot on your aiming point. Then move the dot to the center of your pattern. Makes the attempt much easier if your by yourself.
When your doing this remember you don't need a red dot to hit a turkeys head and neck at 30 plus yards. Its on there to hit them close with a single barrel gun. So always go back to 15 yards or so and make sure your dead on :).
Good luck :).