Raimey,
Its not a matter of what is acceptable to me,those dimensions would match the ones shown for cartridges in the several references.Of course, I guess you could measure it in chains, if you tried hard enough.What about Rods?It would be a pretty small fraction though.
I agree with Jani that it is likely 8.15X46R.Even though this cartridge was mostly a target cartridge,it was also used for Reh(Roe)hunting as evidenced by being in a drilling.One of my German friends used a drilling,so chambered,at least to the 1980s, to deadly effect( always a neck shot at base of the skull).
Mike
