Thanks Colonel. In that case perhaps better that I change recipes.

Now can anyone explain why the same proof house (Eibar) would identify different proof pressures (e.g. 1000 kg/cm sq, 900 kg/cm sq, 850 kg/cm sq) to similar game guns (not "magnum proofed" guns) of similar era? All such guns seem to be stamped with the same 850 kg/cm sq (850 bar) proofmark.