I would like to know the molecular structure of these before I bought one. If it is some injection molded polymer made from recycled milk jugs or something I would pass, that's just me though. If the parts are machined out of either Delrin or UHMWPE, then it might be OK. Delrin is great, but I have also seen it catch fire many times much easier than the UHMW. The UHMW on the other hand is better at impact strength and such, also has a much higher melting point (these are hot gas action guns), but scratches easier. I would like to see a stress test on one of these firing a few hundred rounds pretty quickly to see what happens. Might be a good use for a dedicated .22 upper.