I, too, remember seeing them in the DGW catalog. I never did see one in use nor ever hear of anyone actually using one for its intended purpose. I am no lawyer but I would expect that the use, loaded or blank, would be illegal. It would be considered a ****y trap and their use is a federal crime. If they actually injured anyone, even if it was the flame of the discharge of a blank, it would be not only a federal crime but would also result in a sizeable lawsuit. If I had one, I would use it as trading material because if it won't shoot a ball down range accurately, I don't want it.
Ya know, I wonder if any houses ever burnt down as a result of the use of one of these devices?