Hey Lonnie,
I can answer this one...the rear site dovetail on an artillery luger is physically part of the barrel... I don't know if they were machined from bar stock or were forged into that shape and drilled, but they are definitely not soldered on like a 98 Mauser rifle rear sight base usually is.
This closeup is of my "frankenartillery" luger rear sight base. You can see the whole pistol in the old Owner's Corner under my name... It is a parts gun made up of 1914 Erfurt parts.
The gouges you see in the rear sight base is where some amateur clamped it in a vise to attempt to remove the barrel from the upper receiver... fortunately for me, the previous owner did not damage anything else...