I would say, simply based on who jinx is and what she does, they are a mixed bag. I am imagining that The Zapper is more of a Hextech weapon. It's elegant, it's shiny, it's got good clean feel, its got long range, and its bloody strong.
For Fishbones and Pow-Pow though, I'm not sure if they are chem-tech. Hextech is generally really smooth and ornate, a lot of flowing designs and light and shiny bits. Chem-tech is more visceral, more gritty. It does the job, and it does it fast and effectively, form means nothing. Dull metal mostly defines chemtech, that and the exposed chemicals and flames that attune each one.
Fishbones and Pow-Pow might be chemtech, but only because they lack the smooth visuals of more sophisticated weapons like Jayce's Hammer or Cammy's legs. They do what they need to do, and they do it really well.
Plus jinx hangs around mostly in Zaun, she probably gets her stuff from there. Bullets are expensive after all, hextech bullets probably so much more so.