Stephen,
Sounds like you have a commercial HSc. If there is just an eagle N E/N on the pistol and no waffenamt acceptance stamps on the left side of the trigger guard (like E/135 or E/WaA135) then it was never military accepted and was a commercial pistol available for purchase by certain qualified party officials for example. There was around 43,000 HSc commercial pistols produced with what is called a military type finish (meaning less polishing and buffing) and these were commercially available for sale well into the war. These are in the serial range 788000--927000. Not particularly rare or scarce (around 43,000 produced) but if in good shape certainly colectible as a Nazi era proofed (E/N) commercial market pistol. In terms of dating your HSc it is somewhat difficult because of lack of production records but I would say yours is a 1942/43 (midwar) produced specimen. Others on the board may be able to narrow it down further. Hope this helps some.