I had Williams do trigger jobs for my post-ban HK SR9 and Springfield Armory greek-receivered SAR8. I have interchanged the trigger packs on both my rifles, and it functions like a champ. Williams could tell the diff. in the construction between the SR9 and SAR8 triggers. So you could probably get a HK-clone trigger pack and have it modified for set trigger etc without messing with your origin HK. I would contact Williams regarding which trigger packs to get/buy just in case he gets picky, and may not work on it if he sees a problem or makes you do extensive mods before he will do the work. I had him do the trigger job on my original HK trigger, and what he is not visible to my eye, externally it looks like just an ordinary HK trigger pack. I had the level one trigger job done, and man it is the difference betwen night and day. Dropped the original trigger let-off down to 5.5lbs from 9lbs .