@removebeforeflight - before the war, all guns made on contract received contract numbers, not serial numbers. Furthermore, the contract numbers all started at the same number. All contract numbers were numbered between 0 (well something larger than 0 but i don't remember which number) 200,000. Contract pistols typically included a roll mark indicating the country or department that ordered the pistols.
Pistols made for commercial sale were numbered above 200,000 and those were serial numbers.
During WW2, while under German occupation, the numbering scheme was changed.
Still more confusing, a large number of records from FN were destroyed during the war.
I haven't studied post-war pistols as diligently but FN did not follow the same numbering schemes as before or during the war.
Lastly, FN is very protective of their records. Very few people outside of their facilities have ever been granted access to those records.
This means a number of things.
1) there are multiple contract pistols all sharing the same numbers. (e.g. There may have been a Dutch contract pistol with contract number 12345, and a Serbian contract pistol numbered 12345, etc.). These pistols could have been produced a decade apart.
2) you have to know whether your pistol was produced pre-war, wartime or post-war for any serial number chart to have any meaning.
3) there will be post-war pistols that share serial numbers with pre-war contract or commercial serial numbered pistols.
The style of grip panels on your pistol were introduced by the Germans during WW2. This styles was continued for a short time after the war. It is possible the grip panels were swapped. Who knows. There are a few minor design details that would define it as a pre-war or post-war pistol but I would need to see it side by side with known examples to be able to tell. I still believe your pistol was produced a few years after W2.