Test prop is one that will cause some pip. I don't use a seperate needle to draw. The large gauge pins can damage the stopper over time. It takes a minute to draw using a 23g pin, and your pin isn't going to be dull to the point it is a problem.
Are you reusing your larger pin? If so don't. They are cheap. Use a fresh on each draw.
If you have injected the same gear with no pip, thenthe problem is most likely from a bad injection.