The National Firearms Museum has a short on the British Nock Volley gun. I didn't realize that the simultaneous discharge of all seven .52 caliber barrels could break a man's shoulder. Scroll down from the Link
I'm just suprised that someone hasn't tried reproducing it in a more shooter friendly caliber- such as .36 or .40 just for the heck of it.
I'd buy one.
I'm just trying to picture in my mind's eye how the flame channels would go to all the barrels, as getting all that right would have to be a nightmare, as well as cleaning it...but to be the only feller with one- ah!