H&K USAのサイトにもちゃんと記載してあったぞ。ただMP5K PDWもしっかりPDWだと書いてあるw

http://www.hk-usa.com/military_products/mp7a1_general.asp

In response to the NATO PDW requirement document D29, HK developed a Personal Defense Weapon system
that will penetrate the CRISAT vest, comprised of 1.6mm titanium plates and 20 layers of Kevlar,
out to 200 meters and beyond.