We are very limited on inventory of older models, if we have any at all. It looks like we still have this iron head available. Have your golf shop order it through out Customer Service Department.
Iron Finders has a used one with a metal shaft in stock, if the parts bin at Titleist turns out to be empty.
Make sure that your Golf Pro asks for just a the 710 AP1 4 iron. We do have availability for just that iron. There is a chance he asked about 710 AP1 in general, which means our Customer Service Team would have checked for all iron heads.
Let me know if you still have any trouble.