Regarding the headstamp where the arsenal model “54” stands alone, my only green ullet Tokarev round has the same headstamp. The case shows no signs of being recycled. I have a hunch that the ones with this headstamp were specifically for that loading. Two reasons for my gut feeling on it - I have only seen or heard of the headstamp on these special rounds; I doubl the headstamp would have met Polish Military regulations for tactical ball ammunition.
Just a theory, yet to be confirmed OR denied by any Polish collector, and no documentation on the subject at all that I have found so far. Of course, I can’t read the polish book on ammunition, a very good source for those that can, so I don’t know what it says on the subject, if anything at all.
Partial headstamps on rounds made by primarily military factories but for police use are not unknown, or for special-purpose cartridges for agencies other than the military. There is a frangible 9 mm made in England with a partial HS, and I have seen others. One of the .30 Pedersen rounds made at RA has only RA on it, but for what reason, I don’t know. I am sure there are dozens of other examples.
This is not to be confused with headstamps that have only dates, or caliber or information other than the manufacturer’s designator, which are generally made to conceal or confuse the identifiy of the factory making the ammo, or who it was made for, or both. That is a different topic altogether, of course.