What do I have here?

[Lugerdoc]

I agree that your E/6 military accepted mag started its life from Simson and later renumbered 4466 with non-traditional dies. If the police had renumbered it, I'd expect the die size to be the same as the 2 stamped above the S/N. Is there a proof on the right side of the barrel extention? Hard to tell from your photo. This may provide more info on who & when your luger was converted from a commerical. Tom H.