Right back at you:
Why in your opinion does that variation at 100 yards in the Canadian1945 Shoot To Live become an explanation for DELIBERATELY sighting in with a 2.5 MOA error at 100 yards - an error that then increases the error of the POI versus POI as the ranges increase after that?
An error, BTW, that wasn't used in sighting in by Canadians BEFORE the 1945 pam was published, if that 2 MOA variation is the explanation.
And also BTW, an error that the Brits chose not to change their zeroing procedures to emulate the Canadian pam after it was introduced?