BCC

This is a hornets nest but a worthwhile issue. First, like collector cars, there are specific qualifiers. Such as:

1. Factory original=100% parts and finish THAT came on item from the factory.

2. Issued or as Used condition= All period (my be police or army rework, will show some wear and use etc... but as captured by the GI or last used by the German.

3. Original parts/period correct= some parts replaced with CORRECT period parts....but done after capture or 1945 ( whereever one draws the line)

4.Post war offical refinish= example the VOPO and Russian Lugers...these are offical respective government reworks..but done post 45.

5. Post war restoration=post war refinish but original in style and look.

There are at least several other specific categories that one can look at but I think that it is most important to really understand what you are looking at and its context.

You question is important but not simple. The pistol used to kill president Lincoln had some wear and damage...and I believe a non-factory original screw somewhere, this may not be finnest example of a Derringer in exsistance but it has been thankfully kept in the historical condition and context that it was recovered at Fords Theatre. If a "collector" had gone in and replaced the screw with a "correct" one and had re-finished the metal and wood to Factory specs....much would have been forever lost. Many weapons were mis-matched by the Germans (esp. the last couple of years in the War) this does not make them trash and non-collectable....I can show you mis-matched Confederate pistols that have brought in excess of $20,000 , so be carefull what you put down!