Just off the cuff, I don't think the Brits made many sub-gauges during this period and may have imported all small-bores. There was an exception in the Belgian prooflaw that allowed the makers to send a weapon, devoid of any Belgian proofmarks, in the white(maybe further completed???) to a foreign Proof Facility. If we could see all the areas where touchmarks pool, migrate, wad up, additional info may be garnered.

Serbus,

Raimey
rse