The forward section of the receiver is split, and the barrel has an extension that’s headspaced with a jam-nut similar ... The bolt has a AR10-style extractor and an M16-like plunger ejector ...

This modules in this file create standard ISO (metric) and UTS (English) threaded screws. The screw() and nut() modules produce screws and nuts that comply with the relevant ISO and ASME standards, ...