Doc; Will have to try to do some more digging on this, but generally I think pressure began to supercede load for proof shortly after the introduction of smokeless proof. W'with BP the pressure was actually pretty well controlled by the load, but this was not true with smokeless. This has often been stated to be the reason so few pre-1912 German guns bear Nitro Proof. German proof law at the time required proof "By Load" with whatever powder was used for proof. This resulted in a "Very Severe" proof when smokeless was used, so few makers submited their guns for "Nitro Proof". This changed in 1912 with the law being re-written for nitro proof to be done to a pressure level rathar than by load proportion. Some other nations I beleive were already doing the same, in fact may have been done from the beginning of Nitro proof in England. These pressures were not always necessisarily published, but the proof athorities & gun makers new them.
