You used to be able to order stripped receiver sets through the FN custom shop but they shut that down this past year because it wasn't getting a lot of traffic... If I were you i'd just buy an FN 15 and part it out, use the receiver set for whatever you need it for and you have the 16" FN barrel to use or keep as a replacement (great barrels). Or get in touch with your local FN dealer and see what he can do for you