7.62x39 - hs - 0381 706 . What do the zeros mean ?
Do you have an image for us?
I can not answer your question, although I have heard several speculative answers to this question over the years… I also know of “0501 704” on 7.62x39mm tracer and “031 704” on 7.62x39mm Ball cartridges.
Whatever it means, it does not appear to have been isolated to just one factory or year.