The FGC-9 is a hybrid design which uses a steel barrel, bolt and springs.
The design was meant to be made with a minimal investment in tools, using widely available steel and springs. One of it’s major innovations was the homemade, relatively high quality steel barrel. It uses the strengths of both 3D printing and commonly available steel items to produce a firearm approaching the longevity, accuracy and reliability of low end factory produced firearms.
OK, that is what I was thinking. Thank you for the explanation!