One of these days I'm going to contribute something rather than keep asking questions. Here it is, does anyone have, or have used, or know someone who has. I've seen the video and they look pretty nice. Im talking about the slide fire, it is a stock adapter that allows very controlled 'bump fire'.

I haven't tried it myself, but my son tried one on an AR. It worked amazingly well. Not quite as fast as a true full-auto but pretty close. He had trouble with accuracy but I think a little trigger time would solve that problem. All in all, I was impressed, and it's a whole lot cheaper than the real deal!