Model 1921 misssing in action.

Thank you for all the input guys. After doing the research here at the luger forum, I'm Positve it was a Portugese Navy luger. I remember that there were other marks on it , but after scanning the proof marks I found here, they all seem to run together. I know from the letters that my father had the luger in his posession prior to Pearl Harbor. He brought it over to Cairo/Alexandria when he worked for Curtis Aircraft in North Africa.One would think that as part of the identifcation that they would have mentioned the finish if is was nickle or chrome, since that was an uncommon finish for a firearm of the time. However, it has had the finish for as long as my father had it. He said that it had alwasy been ....nickled?..could be i don't have an eye for it unless they're side by side. It seems logical that a seaman however might have had it plated for the protection from a corrosive eviroment....any thoughts? As always your comments are welcome. I have a slim hope that a picture may exist if my friend and shooting partner in OR comes through. We had a Photo biz in CA about 12 yrs ago and may have used it as a prop or in a test shoot for our Porfolio....keeping my fingers crossed. thanks one and all .