Just wondering if anyone could suggest a 9mm upper that uses Glock 19 (or 18 or 17 I suppose) magainzes. I've been considering a Marlin Camp 9, but for the price, I could practically put together my other AR lower as a 9mm. The only thing I really liked about the Camp 9 over ther others was that it took the same mags as my S&W 9mm. Since I also want to purchase a G19, I figure that I could get the same effect by building an AR that takes the same mags. Anyone done this?