Looks like we might be having a communication issue here, Martin. I never said there was supposed to be a serial number on the Slide, so I don't know where that came from. Only the wartime HSc had that marking and I don't see any in the photos.
Secondly, the WR stamp is on the LEFT side of the Trigger Guard web. I never said there was supposed to be a mark on the right side. Again, only the wartime HSc had a Test Firing Proof Mark (Eagle/N from the Ulm Proof House) on the right side.
And finally, from the photos it sure looks like this pistol has a blue finish and not phosphate. Are you sure it's not blue? So, bottom line, this HSc is a good example of Post-War production.