I don't know what the story is with plastic frames - they may be made deliberately with an open tolerance. The barrel to slide interface is more likely to need fitting, I'm guessing. In either case, it's not a matter of interchangeable, just of fitting. Anyway, please do post an update; I'm interested.I will contact them and will try to update this. I didn't know or think about the slide having to be specifically fitted to my frame. Is each gun of the same model(SR45) manufactured that different to where the slide would not be interchangeable like that?