At a local gunshow this past weekend I got to examine this round.
Rim diameter: 11.84mm
Base diamter: 11.61mm
Shoulder diameter: 10.65mm
Neck diameter: 8.61mm
Rim to head: 2.81mm
Rim to shoulder: 40.3mm
I have no idea what this round is (assuming that it is legitmate) or what it is based on. It looks not unlike a 6.5 x 50SR Japanese, but the extractor groove is not as big (tall). The projectile has a CN jacket.
The primer is brass and there is no headstamp.