The RWS code during this period is Lettter-Number-Number-Letter. I initially thought Box #2 may use this code (B1C) except RWS codes all have two numbers betweem 41 and 71. Nothing else on this box fits an RWS code. The “OY” could be a Geco code. “O” is 1934 according to what I believe to be the Geco codes.The months codes are not known.
Box #1 with code PK would be 1934, and the PK code shows up on a Geco box of 38 Auto with an Astra label which dates from about this time.
Box #3 has code “SC” . The “mpv” suffix is relatively common on RWS boxes made by Geco, but the meaning is unknown to me. S would be 1937.
Both K and C are on the tentative list of month codes (though what month the codes represent is unknown. Y is not on the list, but there are other letters in this second position on the Geco code that are not on the list so the list could have changed over time.
These dates make sense since “Oeldicht” Is stamped on Box #2 indicating use of a box printed before about 1934 but used for the early Oeldicht cartridges. The other two boxes have Oeldicht printed on the label which would make sense for post 1934 boxes. It is interested that only one box has SINOXID printed on it since this primer was introduced in 1928.
Remember that during this period, all production of “RWS” autopistol cartridges was actually done by Geco regardless of the headstamp or box label.
This is my best guess based on the RWS and Geco boxes I have documented.