RB
#7 and 71/2 is all i use for turkey in my 62 at 20 yards she flat rolls the bird .
if your not taking head shots , you should be .
if you doubt your load , regardless of what you use , you need to do a penetration test .
For this I use a piece of ¼ inch ply or just a sheet of paneling . Either of these are much tougher to get through then a turkey neck or skull
Once you find your load for pattern , place a new target on the ¼ inch sheet . Mover to your distance and take a shot . Then go look at your target as well as the back of the board . This will give you a good idea of how well your shot will penetrate.
The reason I say head shot is that the feathers work really well to slow down the shot . . Next big bird you get , look it over for shot .
I have found #3 and 4 sitting just under the skin of the tail on a couple birds as well as healed shot in the breast