I have 24% science, and try to farm some BG guns, or ammo, so after killing 3-6 khans, i have to do something with their stuff (jackets, leather armors, greases, fn fals, shotguns). Each group gives me 1-5 metal parts, shitloads of gecko pelts, fibers, wood, alloys. But i have to admit, that HQ materials are really rare.
I'm pretty sure khan loot doesn't hand out hq parts.