[Ron Wood]

I can offer an alternative WAG. The observation the inspector initials are a bit haphazard, i.e. two initials or three, upside down, off center, etc. is certainly the case. My guess is that these may be an inventory inspector marking when the holsters were bundled with the Lugers to be shipped to individual field units, while those going to state-side garrisoned units may not have had the same requirement for accountability and therefore are sans initials. Furthemore, the "HD" initials seem to be recurring unless the same holster has been published in multiple references.