Another issue/question is centered around just what was the state of the double when it was issued a serial number? Was it a block of steel, in the white, etc.? It was stock and stayed on the shelf until an order was to be filled and in that time frame it visited the proofhouse. If it is devoid of a date stamp(pre-1924) the considering WWI, it could have been on the shelf until post WWI and prior to 1923. Many time one sees preliminary proof on the tubes and then again on the flats. Also I think 2.5mm to have been the breaking point for reproof. So as some think, what if the chamber was 67mm +/-, then an additional 2.5mm could have been cut without reproof.
This is a bit off this topic, but what about all those claw mounts on doubles, or drillings, that are pre-1900? I guess circa 1900 to be the earliest date for a scope and Zeiss had an offering in 1904. At some time these pre-1900 black powder rifles had to be retrofitted.
Kind Regards,
Raimey
rse
