Sounds like you are using a Hornady comparator and measuring to a datum on the shoulder using the 0.420" insert. I have measured new 7mm SAUM cases and get a result close to yours. I work in metric so will take a little time to convert my results but I wonder first why do you want to set your shoulder back from fired so much? and if the cases sized chamber freely what is the problem? Will get back to you a little later with more.
Regards Grandpamac.
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