First, I cannot date any of the various USCCO bullets. Based on my collection, I believe there are five different bullets used by USCCO on 9mmP. They are arranged from right to left below in what I think is their order of manufacturer. The dates are pure speculation.
Far right: CN jacket bullet with the same ogive as the USCCO made MAXIUM headstamped 9mm Glisenti cartridges made for Italy in WWI. The 9mm Luger cartridge first appeared as far as I know on a 1919 supplement to the 1917 catalog. This cartridge occurs with both US stamped brass primers and unmarked copper primers. I have both FMJ and HP loads with both primer variations. There is no marking on these bullets. My guess is that these were produced from 1919 until the mid-1920s.
Second from right: Tinned bullet with the Glisenti ogive. This is the most difficult to find in my experience. I only have it in FMJ with a US marked brass primer. The bullet is unmarked. These were probably produced from the mid -1920s or so just before the takeover by Winchester.
Middle: Tinned bullet with a lower shoulder than the Glisenti ogive, and an S mark on the bullet. This is a HP load. I do not have a similar FMJ load. The primer is a typical Winchester nickel primer of the period with a purple seal. note the smooth case knurl which is different from the earlier USCCO production and typical of the Winchester production of the period. The bullet marking is also typical of the Winchester production. I suspect this is a transition round from the 1926-1928 period. Again, a difficult load for me to find.
Second from left: This is a tinned bullet with a typical Winchester ogive. It has the S mark and the typical Winchester primer and seal. I have this only in a HP load. I suspect it is from the late 1920s into the 1930s for a bit.
Far left: This load occurs with both FMJ and HP GM jacket bullets with an impressed S. These are identical to the Winchester bullets except for an S instead of a W marking. The primer and seal are also typical Winchester. These are probably the last production with USCCO cases so are likely from the 1930s until the end of “USCCO” production.
The initial Winchester 9mm Luger ammunition has a headstamp: WRACO 9M/M LUGER AUTO. At some point the headstamp was changed to WRACO 9M/M LUGER. I have a cartridge with this later headstamp, a copper primer with a purple seal but loaded with a typically USCCO CN Glisenti ogive bullet, but this bullet is marked with a W!!! It appears that at some point in the 1920s, early style USCCO bullets were supplied to Winchester and marked with a W. The bullets loaded in the earlier style Winchester cases have the very low shoulder of the later USCCO loads so this W marked Glisenti ogive bullet really stands out.
None of these stories is simple which makes cartridge collecting so interesting.