Mike,
I took your posted jpegs and lightened them up a bit with photo software...I cannot be sure...but they do look like brown and not black grips...see Gibson, page 46 when you have your new book at home.
More importantly...do you own an HK luger ? If yes, we would love to see photos of the entire gun...!!!
Here is a link to LF member, Leon DeSpain's web site showing a pair of really nice Ritzmann grips for sale. As you can see, your grips are not Ritzmann type...
http://lmd-militaria.com/page280.html
Regards,
Pete...