Ever wonder who the outdoor writer was that convinced the Turkey world that we need to count how many pellets are in a 10" circle....and that was the best judge of a Turkey gun ?
I cannot say who, but I can say when. It would be some time after 1982-- maybe later than 1988. I say this, because when I got into turkey hunting in the early 80's, the rule of thumb was 2 pellets in a dixie cup at whatever yardage you were shooting. There were no dedicated turkey guns or choke tubes or turkey ammo. That came somewhat later.
When I got into the sport, turkey hunters were mostly still using 12 GA trap guns with 2 3/4" loads. If you had a 40 yard gun, it was a peach. The minimum was passing the dixie cup test at 20 yards.