[mrerick]

From your closeup picture several problems are evident.

First, the frame is proud of the receiver a few millimeters. This would never leave the factory that way.

Second, the barrel to receiver witness mark doesn't line up.

Third, it's evident that the frame and barrel have been renumbered. The vertical grind marks on the frame and the difference in depth of the barrel serial number and gauge mark show this.

The "S" (probably intended to imply a Simson rework) and "M" (probably intended to imply a Marine pistol) die fonts on your gun were not used by Mauser in Germany. They had to be applied later.

All of this is unfortunate if you were told you were getting an original factory gun.