[mrerick]

Note that anything that fills the markings can also be obscuring the details of the markings themselves, and any manipulation that may have been done to them.

It is very common for a person that restores Lugers to use an engraver to enhance or restore markings. This would be clear if you could see the profile and detail of the marking, and that detail would not be visible if covered with the residue of a lacquer stick or marking pen.

Take photographs in indirect (shaded) sunlight with a camera that can be properly focused and which you can adjust for exposure and you'll get the best pictures. That's especially true in today's world of digital photography and high dynamic range sensors.

Also, use care with acetone. It can dissolve or soften the bristles of some toothbrush construction as well as the shaft. Start with isopropyl alcohol. Follow cleaning with a preserving gun oil.