This reminds me of a friend with a starret ruler, about 18\" long I would guess. The ruler is OFF by about a quarter inch in length calibration. Very strange indeed, but we checked it very carefully and it indeed is way off in its calibration. Naturally, my friend noticed this after trusting it to make some parts. This is a real mystery! Maybe a factory reject that somehow made it out to the public? He still has it for conversation purposes, plus no one would believe it unless they seen it for themselves.
George