Looking through the bore, and using a metal straight edge, has clearly indicated the can was off center. It wasnt snugging up to the shoulder enough to sqaure itself.
A shim appears to "straighten" things out. Literally!
I also have several thin shims for zeroing with the least POI shift.
After my next range trip I'll post the result.
I learned a lesson: Pay more attention to first time can-to-barrel matings in the furure.