Do the 9mm and .40 M&P's share the same frame? I've got my M&P in .40 that I shoot limited with. What I'm wondering is if I could pick up a 9mm slide, drop in a barrel and a comp, and add a Burris or Jpoint to it. Pick up some 9mm mags, and 170mm extensions, and go to town. Would it work? Will S&W sell me a 9mm slide to do it?