The headstamp styles are confusing, as I have some FN22, FN22 2 39,
37 C and 38 D, and other variations ( 4 stamp Bandoeng/Soerabaya reloads-- up to 1940).
All these cartridges came directly from 1980s Indonesia, and some from Dutch colonists in the 1960s when West Papua was handed over to Indonesia.
So it is not correct to say that ALL Dutch ammo after 1920 was with a “four stamp” layout. It is well known that the Dutch bought Empty cases as well as Loaded ammo, and some were loaded at a later date (but maybe the same year)…The KNIL ( East Indies) had their own complete Loading and Reloading facilities in Java —but NO case drawing equipment…the first attempt at this was the ordering of a complete Line from Australia in 1940-41 for .303 manufacture, which didn’t eventuate, because of the rapidity of the Japanese expansion in 41-42.
Ammo suppliers in Holland proper were AI, and Hirtenberg–Dordrecht; foreign suppliers were FN ( 1922 is the only one I am familiar with) and possibly some German suppliers pre-WW I (?Polte?). Due to the loss and destruction of a lot of 6,5 ammo in Holland during WW II, not a lot is known about the headstamps of this period (WW I and 1920s) from samples seen. The texts are very helpful, but are not the full answer.
Any further clarifications would be appreciated.
A V Ballistics.