Where, exactly, is that .028", and what is the MWT at the end of the chambers, the forcing cones, at 6", 9" & 18" from the breech? If the seller declines to share, I'd pass.
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https://docs.google.com/document/d/1ZIo0y746UsSRZIgRuuxwAbZjSBHitO_EanvwLYc-kGA/edit