As far as I know, no one had figured out the DWM codes. BKIW was used by DWM from June 1933 to June 1936 so that gives you a general time range. There is a 9mmP box with a similar BIWK label reportely stamped 039 AVE. 028 AEV is on a red 20 round box of 7.63M but is not marked BIWK, thought it may be a contract box, not commercial.
but there are quite a few other BKIW marked boxes in a variety of calibers with the stamps listed below:
I had hoped the first letter was the year, but there are 7 first letters(A, G, I, L, P, U, W). Perhaps the letters cover 6 months each like Remington used, then June 33-June 36 would require 6 letters, but perhaps they continued to use the labels for a bit after the name changed to use them up instead of throwing them away so perhaps 7 letters were used for Load Codes!
I have tried to figure out if the letters showed the day an month but have had no luck. I also have no idea why there were sometimes one letter, sometimes two and sometimes 3.
There are commercial rifle rounds with 5 numbers ahead of the letters HA which may be a different code entirely.
Codes without the BKIW marked labels have the following first letters
A, a, E, L, s, T, U, V, W.
If anyone has other DWM box labels, particularly BKIW marked, please post them or send me an email describing them. images like Peters are the best.