thanks for the replies;
My feeling on it is that it started life as a Simson (the spine is not marked, thus probably an armorers replacement magazine). The "542" could also be for 542a, not all the "a" suffix mags were marked that we've seen.
Being police, well, I don't know. The luger has no sign of being a police, but the luger was issued in 1925 / 1926 time frame and sear safeties were not required until the 1930's, and not all police were equiped with sear and/or magazine safties.
Who knows, but not a likely 'faked" item.
Pete, rough night or no wheaties to help the day go better
