The German state of Nordrhein-Westfalen (Northrhine-Westphalia, or NRW) purchased and issued several thousand FN Hi-Powers in the 1950s, and they remained in service into the late 1960s if my memory serves me right.

These pistols did not get any state stampings or other identifying marks, as these did not become required in Germany until 1968, and NRW did not mark any guns acquired before then (in contrast to some other states like Bavaria and Lower Saxony, which went back and stamped every gun they had).

So the only way to identify these Hi-Powers is usually that they come with a holster with German markings.

However, I have a source I can check where I might find some serial data. I’ll add any info if that turns out to be the case.