Is it possible to place guns that flip "ready" when shooting, or without pointing them forward stationary?

I'm trying to build Gundam-esque or Armored Core-like mechs with guns that "should" flip forward (either from the back or from a downward position) when shooting, but the models just flip flop around the joint they were placed on. I was wondering if anybody ever actually figured out how to do this? Please share your solution.