I did some research on this when I thought about purchsing one. The forearm will fit with some modifications. The rear attachment point has to have some material removed and the front attachment point is some sort of clip and screw rather then a pushpin style like the HK91 (according to the experts at HK91.com). The rear stock supposedly would have to removed from the receptacle and the plastic stock attached to the recoil spring/reciever cap assembly. The guys over there can probably explain this better than I can. Just check out some of the old topics over there at HK91.com