I have two muzzleloaders having laminated steel barrels with London proof marks:
In one case the barrels are marked on the underside with a definitive proof mark, the gauge (14), a view mark, a provisional proof mark, the gauge again (14) and at the breach end "B10".
The other ML has barrels similarly marked except without a provisional proof mark. At the breach end the barrels are marked "60" or "09", depending which way is considered right side up.
Does anyone know what the mystery numbers at the breach end signify? Thanks.