Good points, I also see a LOT of salt blued DWM, and Erfurt Lugers with those edges. Look for these signs on those Lugers for refinish.
1. No paint in the safety marking
2. Blued in the magazine well and inside the forks of the receiver
3. The finish "feels" waxy when you rub your thumb across it.
4. Bluing looks thin.
5. The absence of polish cut and/or tool marks, DWM and Mausers were polished differently
6. A blued muzzle
7. RED paint in one of the thumb safety "dots" (two small dimples in the frame ears)
8. Look a the flat ares in the light, you can see the light reflect a bit wavy indicating the flat is no longer flat.
9. A blued firing pin or hold open on Erfurt or DWM Lugers
10. OVER polish to mirror under the bluing.
11. No wear on the sideplate island flat, or on the end of the frame side rails.
Any Luger that has a finish that is 100 years old will have been in a holster a few times, unless it has not been in war or preserved very carefully right off the assembly line. Sides of the muzzle barrel band will show wear, high edges on the recevier forks, etc
12. BLUED parts that should be strawed or fire blued.
13. Mis matched parts, or engraver pen marked parts, different height of letters, numbers, fonts on parts.
14. Grips that look out of place, non issue grips, ie Black Widow grips on a DWM.
15. Grips that have a fat edges or really bad checkering.
16. A hold open on a DWM or Erfurt should have a small area on top that you see fireblue to straw color, with the spring in the white and the larger block in the white.
17. An original rust blue will usually show some brown color in strong sunlight.
18. Straw parts on an original gun almost always will show whiter color on oneside of the trigger where the index finger has been drug across it, the bottom of the safety lever can look whiter than the top of it.
19. A original Luger should show some evidence of firing from the toggle stamping the rear of the frame by the lanyard loop area at the very back of the gun.
20. The area on the right side of the frame under the right frame rail should show some remainder of longitudinal tool marks (lines) if it is a Military model.
21. Inside of frame ears flats should have either circular tool marks or longintudinal tool marks that looks like lines at different angles, a MATTE look in these areas that has been salt blued really sticks out.
Any number of these things MIGHT be found in a Luger that is overbuffed and reworked. As a restorer, I try to mimic the original condition as best I can. The rounded edges shown by Postino IS the absolutely most graphic indicator of a amaturish reblue. The frame ear edges round over REALLY poke my eyes out!!
