Proof marks onGrip Screws
 

I have a DWM double date luger which is double dated 1918/1920.
The pistol was at some time worked on at the Ulm factory since is has the antler mark on the frame. The pistol has proof marks on the grip screws, a Crown over a U it looks like, which I believe is a firing proof, not sure. Would the Ulm factory people have proofed the grip screws after their repair, and would the double date been added at the ULM factory repair?
I have never encountered proof marks on any of the grip screws on any of my other Lugers, so just wondering why they would proof mark the grip screws after a repair. Did they have some type of indicator as to what repair was done when repairs were done?

Grip screws are from an Erfurt Luger, they marked most parts

They would also be from 1910 - 1914 as 1914 is the final year that Erfurt marked grip screws. Erfurt made no Lugers in 1915 and when they resumed production in 1916, grip screws were not marked.

I appreciate the info, but it is somewhat confusing as to why Erfurt grip screws would be on said pistol, unless Erfurt supplied parts to the Ulm factory, I suspect it is one of those areas where there is no definitive answer. Again I thank all for the inputs.
B

If it was commercially proofed at Ulm then the chances are that it was repaired at some point. That repair may have included replacing the grip screws. (That alone would not be cause to be proofed again. Re-proof is done after replacement of certain parts such as the barrel, breechblock etc.) The screws may also have been replaced many years before that. As you say, there is no definitive answer to that question.

Could have been replaced by anyone any time. Bill

Good item to sell or trade, too!