There IS a cure for your problem! Your actual zero is the cold bore shot, with the rest walking in an group differently placed than actual cold bore zero. Dillinger is correct and has beaten me to the post (as usual). What you need to do is have your barreled action (or just barrel) cyrogenically frozen to relieve all stress. Simply send it off to 300 below for their treatment. It's worked wonders for MANY rifles I've barreled/built-even to the point of automatically having it done if the customer approves.