When I bought My Benelli M1 90 the steel shot for waterfowl had been just introduced .With the MOD choke I was getting XXFULL with steel BB. I was working out things for Goose. I thought about it and realized it might work on headshots on geese.It did !!
Aim at the head , no more 'tail feather ' problems ,few pellets in the body.
With shotguns you must always pattern your loads .You might find surprizes like I did. Look for even distribution of the shot within a proper sized pattern for thr turkey head.