I don't believe we've established a date on Tut's gun yet. The information I have is from a 1972 Gun Digest article, indicating that the standard smokeless proof (PSF indicating smokeless) was 12,000 psi. The superior proof, instituted in 1962, was 17,600 psi. Could be that the Italian proofhouse rules have changed since 1972, but if Tut's gun was made earlier than that--and there should be a Roman numeral date code--then I'd say the lower figure applies.