True, but recently (just now, in fact) someone posted a pic that is allegedly KJ-600 in flight accompanied by a flanker, and it also has green primerI'm not sure if primer colour is necessarily decisive, because for all we know that may just be the primer colour that all recent SAC built aircraft use these days.
A good way to verify would be if we had any pictures within the last few years of J-16s under construction and their primer colour
edit: just in good measure, here's the pic I was refering to