Odd K Date Repair Proof

[Thor]

I have a first variation K date in for restoration, it had been buffed and Salt blued on all the gun and small parts. A curious proof was found on the left barrel just below the O:37 proof. There is also evidence of part of the SN buffed adjacent to this location. I am attempting to take a good close up picture but we are in a snow day here in NM with snow clouds blanketing out the sun. I will post pictures soon. The only things I have noticed on this K is no S on the mag button right side flat area and it appears to have an old Erfurt trigger evidenced by the small crown over gothic letter on the top of the right side flat of the trigger and missing S. I also noticed it does not display the little indentations on the area at the front of the reciever between the top of the chamber and each side flat area found on most K date Lugers. I have the blue off it right now.

Thanks for any info, just interesting I think.