Available direct from Vickers Guide:
https://www.vickersguide.com/hk-vol-2

Or from Headstamp Publishing:
https://www.headstamppublishing.com/purchase?tag=hkv2

About a year ago Larry Vickers and James Rupley published the first volume of a series on H&K firearms, beginning with handguns. After some extensive additional photography (part of which I was happy to be able to help out with), they have now released H&K Volume II, covering submachine guns and PDWs. That is to say, the MP5 and MP7 families, along with programs like SMG I, SMG II, SMG 2000, HK50, and HK54A1. They are joined by James Williamson of Teufelshund Tactical as a collaborating author, who brings a tremendous amount of knowledge on the subject.

Where Volume I had a really substantial amount of background text information, Volume II cuts that back a little bit while expanding the photography by nearly 150 additional pages. This is without a doubt the most comprehensive photographic work on the subject ever done, at 550 pages long. The MP5 is the largest section for obvious reasons, and it begins with the earliest surviving prototypes and continues through the most recent product improvements. In between, we see things like the early tactical light systems, the different covert briefcases, cutaways, and more. While I wish there was a bit more historical reference data on some of the less common variations, it's still the best resource currently available on the topic.