I've been recommending #6 shot for years within reasonably yardages. Carl gives excellent advice and I agree completely with him. A dense cloud of 6's inside of 35 or so yards will get the job done nicely... you don't need heavy loads or magnums or any of the stuff you would want for waterfowl. With turkey shooting you don't have any 'armor plate' feathers to get through - just the naked head and neck and the bones there are covered with a thin skin easily penetrated with 6's.

Here is one shot with a 20 ga and 1 oz 6's at 20 yds

Sell the shells to someone from California and buy yourself some lead.