For the record, here is my submission to the 9mm witness mark fest.
4331u is a Rif blank toggle police pistol. It has only the full suite of army acceptance and proof, no c/N.
Since we are discussing witness mark evidence, it occurred to me to examine the Alphabet Commercial Lugers with original 7,65mm barrels which I have on hand.
It appears that what is understood as a complete, proper witness mark is not characteristic of Alphabet Commercial Lugers. I did not expect this result. Haphazard witness marking goes clear back to the i suffix range, although I did not prepare any of these for presentation. It is necessary to go clear back to Old Model and New Model Parabellums and Imperial army P08s to see what proper witness marking looks like.
The reason for non-standard witness marking on 7,65mm Alphabet Commercials is not clear. What is clear, is that witness marks are ultimately not useful for determining the originality of 9mm barrels on police Lugers in the s, t, and u suffix range.
--Dwight