20 gauge, a good load of 7 1/2s out of a decent turkey choke or a good sbooting full will kill more turkeys than most realize.
I have shot about half of my turkeys with a 10 gauge and over half of those were under 30 yards.
I can count on one hand the birds I have killed over 40 with both a 10 or 12.
I am starting to see all of this "turkey" ammo really isn't needed.
Get a bird within 40 yards and smoke him with about anything out there.