Be careful, Others may know better then me but ,I tried some years back to get conversion tables to compare proof pressures. The problem was that British proof use a lead crusher method ,wear as the continentals used copper I was told, so you cannot make direct comparisons.I was also told that the Spanish and Italian proof pressures could not be directly compared either.With the CIP rules it has become standardised across all members. Its still confusing and in Britain in the last 100 years we have had five changes in Proof law [acts] ,marks and pressures in tons ,Kg's and bar's.Measurements in imperial and metric. Now no pressure is stamped ,just a mark to specify standard or superior proof . Confused ? Think how we feel.
