.... There was no minus tolerance on the bore mark as the barrel had to accept the gage of that diameter. Plus tolerance was to the next size gage in the series which varied with each gauge size.
That's a capital point on the minus component. Chambers had a tolerance/variance of >2.5mm(Axel E. gives 2mm but what's 0.5mm??) before it warranted reproof so um one would commmence @ 65mm(Axel E. gives 65.1mm so I guess some empirical data from 100 or 1000 chambers might prove this out?) and range up to the proverbial 67.5mm, which most cartridges are designed. Therefore, if a chamber is 65.1mm plus 2.5mm then it is just shy of 70mm by less than 3mm. But pressure would more than likely be an issue when you jump to a 70mm cartridge.
Cheers,
Raimey
rse
