Creek bottom: First, those wonder wads are not sealing the gases off from your shot. Get some over powder wads and use one under the wonder wad. You will only need to use one wonder wad with the card wad. Then, make sure that the post-it note is wrapped around twice so it will hold the shot. You will have to make 4 cuts in the top of the cup, to help the cup open up, release the shot, and drop off when the shot leaves the barrel. You will also need to use some kind of undersize wad or filler, ( cushion wad -I would recommend getting 24 or 28 ga. wads for a 20 ga. shotgun) inside the tube, with the tube crimped over the wad like you would do with a roll of pennies.
I also seal the crimp on my wads by dipping the crimped end in parafin wax, melted in a small can in a frying pan with boiling water in it. ( a homemade double boiler.) Just dip the cup into the wax while it is still wrapped around your mandrill, and then push it down on some wax paper to set, and remove the mandrill to make the next cup. Once the wax is melted, you can turn the heat down so that the water stays boiling and the wax is not congealing. Then take all the time you need to make as many of the shotcups as you need. If you determine the amount of shot you are going to use before going shooting, you can trim the cups to length, at home, and then cut the slits. The slits don't have to go more than 1/4 the length of the shot column in the cup. In fact, if you play around with the depth of the cuts, you can sometimes get more shot in the pattern. I would back that charge down to 75 grains, as I believe it is powerful enough, using the card wads to seal the gases, to drive the load of shot at sufficient velocity to kill your turkey out to 35 yds. Burning more powder only makes the patterns open faster. That is not what you are trying to achieve.
If the 75 grain charge does not give you enough pattern, at 25 yds, and then at 30, I would not hesitate to back the powder charge down to 2 1/2 drams, or about 70 grains of powder( FFg). That will start the load of shot slower, but it will also keep the pattern of shot together over a longer distance. Most of the extra velocity gained by loading more powder is lost in the first 20 yds, and even this light load will move #5 shot fast enough to kill that bird at 35 yds. The secret is to get more than one pellet in his head and neck. By starting the shot slower, with the shot held in a paper shot cup( use plastic if you must) you can improve your pattern to about Improved Cylinder or a weak modified. That is still much better than what you now get with an open cylinder bore gun.
