Hello Jim,
The lugers I am confused about are the reworks fromthe 1920's era.
If an older piece from the Imperial era was reworked and refinished as many reworks of the 1920 were, some rust left on the gun may have been re-blued over. Maybe some of the advanced folks could give us more advice here...
But the gun we looked over in Reno was a WWII weapon that did have a big rust spot over-blued on the rear grip. There were some other issues with the gun as well. Such as an extractor without 2-digit serial numbers, an extractor that was not "flush" with the top of the receiver, and barrel/frame match-up lines that did not seem to match up at all with one line being much more thickly struck than the other line.
Regards,
Pete <img src="graemlins/yltype.gif" border="0" alt="[typing]" />