If I subtract the .2mm from the marks for each bore I do get very close to my actual measurements. Basically, the bores measure .2mm less than marked.
Regarding post 1962 French proofmarks, which I'm sure had some English basis or influence, after provisional proof and upon demand, the proofhouse would add 0.1-0.2mm to the actual measured bore diameter and stamp it on the tubes/flats. And this is all centered around the 0.2mm or 0.008" tolerance which when met constitutes reproof. For the French it was in 1965 that the pressure designation was changed from Kg/cm^2 to BAR while the Brits made the jump to BAR in 1989 from the 1955 ton/in^2 = 2240 psi = 157.49 Kg/cm^2. So I don't know for sure who was leading the rules of proof horse.
Kind Regards,
Raimey
rse
