True, the shot tube would still be for black powder, or black powder pressures. I would stick with the 65mm on the shot cartridges and a load that would replicate similar black powder pressures of the time. As far as I know and as long as there wasn't any alteration, previous proof efforts under the proof law at the time are still honoured. So I think the scattergun tube was just inspected and a few measurements were taken.
I would think the Ferlach proof facility still has the ledgers.
Kind Regards,
Raimey
rse
