LugerForum Discussion Forums - Luger ID and info

I'm a new member who's been searching the internet for information on Lugers. I found this site and was very impressed with its professionalism.
I'm trying to find out more about a Luger that I inherited. I've filled out the "Luger Identification Form" to the best of my ability. Here's what I think I know.
Toggle inscription is DWM. No chamber inscription of any kind. Toggle knobs are round and knurled. No grip safety. Has a stock lug. 7.65mm/.30 Luger caliber. Checkered walnut grips which seem to be in very good condition although checkering is a little less sharp in places where it was gripped.
Thumb safety is safe in rear position and marked "Gesichert". Proof mark #28 (from the proof mark ID list of this site) which I believe is a Nitro proof
(crown over N) . These are located on the barrel, receiver, and left edge of extractor. Serial number is 8539 with n suffix and stamped in full on barrel and frame. 39 is stamped on other external parts that I can see except the side plate is stamped 33. I assume it must have been replaced. Some parts that I think should be stamped have no stamp at all, such as the take down lever, trigger, mag., etc. Mag seems to be the nickel-tin type with a wooden plug marked "Germany". Barrel length as measured from throat to tip is 3-3/4". It has a milled front sight and fixed rear. I estimate the remaining bluing to be 90% and straw at 95%, although I'm not qualified to do so. The bore is bright and shiny with no rust or pitting and the lands look good.
From what I have determined, the Nitro mark means it is a commercial gun.
What I would like to know is the year of manufacture, approximate value, and anything else you can add.
I have not disassembled the gun to check for numbers on internal parts. It looked pretty complicated in your instructions.
I have not taken any photos yet but if they would help I will. THANKS !!