Premise: The JS 9 mm () is a commercial export version of the QCW-05 (with the exception of different chambering.) It is a suppressed submachine gun developed by the Jianshe Industries (Group) Corporation of Chongqing. The JS 9 mm is capable of using any 9×19mm round, including the popular 9×19mm Parabellum round but has specifically been chambered for the indigenous, armour-piercing 9×19mm DAP92-9 round.
Hypothesis: The popular rounds are 9x9mm