I've bought both the china screws and continuous rails/bearing, all were hardened. I used an angle grinder on the screws while turning on a lathe to take it down past the hardened "chrome" area and then it cut quite nicely with standard HS lathe tooling. In case you're also needing to cut the screws to length, I dulled a bi metal bandsaw blade quite quickly trying to cut the rails (it barely scratched the surface). The rails themselves are hardened (like the screws) and screw mounted every few inches to an aluminum mounting "track". I used a diamond blade in an angle grinder.
Good luck!