Now I know its a 12 gauge, try a load of 2 3/4 drams( 76 grains) of FFg GOEX powder, then 4 OS cards, each one with an off-center hole punched into it, and the cards aligned so that no hole lines up with a hole in the adjoining card. Then put in 1 1/4 oz. of #5 shot, followed by two OS cards. I orient the cards at 12, 3, 6, & 9 o'clock for the 4 cards that substitute for an OP wad: I orient the two OS cards at 12 & 6 O'clock on top of the shot. Then I run a cleaning patch liberally coated with Wonderlube down the barrel of the gun. The lube protects the bore of the gun from rusting during the hunt. The lubed bore keeps lead from scraping off the shot pellets as they exit the gun, and thereby help the outer pellets keep their shape better. Finally, the lube softens the BP residue so that the barrel can be easily cleaned between shots. If you want consistent patterns, you have to clean the barrel between shots.
With this load I have killed pheasants out at 33 yards. I would not hesitate to use it on any turkey I could get inside 30 yards. That is pretty good performance for a cylinder bore shotgun. Unless you use shotcups, or jug choke the barrel, you are not likely to get better patterns than that.
Using the OS cards instead of an OP wad, a cusion wad, and then one Os card on top of the shot allows you to take only the one kind of wads with you into the field. The OS cards, with the off-center holes, allows air to immediately separate the cards, and help them fall out of the line of flight of your shot. If you use the OP wad, and a full cushion wad, you get donut hole patterns, because the heavy wads are drawn to the shot column after it leaves the muzzle, creating a small vacuum at the back of the shot, and the wads " bump" the shot, causing the shot to spread out, giving you a pattern with very little if any shot in the middle. A Donut hole. This is not good.
Jim Rackham deserves the credit for figuring out how to defeat the donut hole effect, and posting this loading data on the forum a year ago.
If you don't have #5 shot, and can't get it in time, then by all means use #6 shot. Just make sure the turkey is inside 30 yards for sure, when you fire. I have some plated #5 shot I was given as a present to try out, but I am not expecting to see any improvement either in patterns, or in pellet energy down range. Save your money and buy ordinary Magnum shot.