Is that the guns ser# (N561623) in the crane cut out along with the Model# 28-2 ?
If it's a factory marking, that takes care of that 'issue'.
I'm not even sure the frame is the control part in Germany.
There is an Ulm Proof Hs mark on the frame. So can I assume that the gunsmithed firearm went thru (Repair)proofing after alteration which it would need to do?
Or is that a left over German Proof mark from orig importation into Germany and before commercial sale of revolver.
It's the only Proof Mark I can see.
Bbl cut of course. The S&W marking redone, likely a pantograph or Laser etch marking. Not unusual in this time. Lots of gunsmithing operations do their own bbl and caliber markings here with such equipment,,why not there..
The frame 'knuckle' looks altered maybe added to and reshaped.
A weld and reshape effort. Again with TIG and Laser Weld, not a big deal.
Front sight refitted, or maybe a new one made and fitted.
Some sort of new metal finish over all. Maybe a hard chrome, hard to tell from the pics for me. Maybe just the lighting in the pics.
There are some blemishes in it. The blotches around the cylinder bloc on the side of the frame suggest some damage to the finish like what trapped oil does to the bluing process.
But it may just be oil on the surface not cleared before the pics taken.
I'd have to really like the gun to go after it and I admit it doesn't do much for me.
If it did then rest would be the normal 'How is the bore and chambers, timing, trigger pull(s), does it push off', etc,,
...and Price