Thatís a better picture thanks for the detail, Iím not seeing the proof remnants but such things can be hard to photograph for sure, the presence of a proof is beside my point however. Perhaps I didnít explain my reasoinging well, but after seeing more detail with this picture I have to return to my prior statement, I believe the receiver was ground before the mount went on, that was the whole basis for my point. Seeing as this is a Borsigwalde you can compare exact proof and serial locations and the numbering would have fallen nearly level with the edge of the saddle that would make for a very obvious serial removal if done AFTER the saddle was mounted. That is my whole point on the subject.

Notice the same kind of numbering/ proof location on Daveís, imagine trying to grind/file those away while in direct contact with the attached saddle, it wouldnít be pretty.