[D P McN]

Thanks to you both for your thoughts.
G2, please see a couple more pictures I took under a reading lamp that may be an improvement for diagnosis, but I suffer from cheap phone. I'm really curious about the "two tone" finish appearance of the mag. The rear half of the mag looks to me to be stainless steel (80% sure) while the front half is nickeled. I vaguely remember some all-stainless Luger mags were made by a firm called Haenel, but they were commercial and I believe were made in the inter-war period. All the WW1 mags I know of were all-nickeled.
Mr. Sweeney, I'm sure for all practical purposes you're right. The book with the picture of the Pioneers with P 04s is "The Navy Luger" by Joachim Gortz and John Walter. I think it's long out of print. At any rate, I'll need to dig it out and take a picture of that page and think it over.