Paul, I saw the after pictures of the proof marks of Herb's gun and the shop did a very good job of striping the nickel without damage to the proof marks. The striping shop has the following link. Their prices are very good for this type of work and I am told they will also remove chrome.
Nickel/Chrome Stripping shop
I can restore your Luger if you are interested.
My site can be viewed at
Thor's Luger Clinic-Click Here