Never owned a Glock, but I'm considering buying a new Glock 24 (.40 Longslide) and I'm trying to check on the authenticity of a particular specimen. I'm trying to determine whether this is a genuine 24, or just a new model 22 with the finger groove frame with a long slide added onto it. I remember reading somewhere that the Glocks have mated frame and slide serial numbers. Is this true? Is there any other way to determine if the slide is original to a new model 24 and not simply a "slap-on"?