[DonVoigt]

I have found that a fine wire wheel is about a close as one can get to the original, military
semi-matte finish.

180 grit is way too coarse, and looks just as you describe-scratchy!
I would go to 320 and if you don't like that, use the wire wheel.

Finish prep changed over the years also on both military and commercial lugers.
If you will tell us what make and model luger you have, perhaps someone can post a picture of one in original livery.