38 • Zips, Pipes, A plumber's helper ...a zip gun made from pipe, plexiglass, tin, and bits of wood. According to the LAPPS lab people, it shoots well. (Courtesy of Los Angeles Police Depart men tj punk hoodlum with a keyholer." The U.S. Army made extensive tests on the keyholing effect of its .223 ammunition used in the M16 rifle. In simple terms, it found the power and energy of the keyholing round transfers very quickly to the target. If that target happens to be human, the result can be a messy, frightful hole. Police officers facing an individual armed with a .22-caliber zip gun are urged to use extreme caution, as a lot of these items are pull-release; thus, dead-finger firing is a distinct possibility. Or, in a hostage situation, the zip gun could be pointed at the hostage and the striker drawn back. Any attempt to disable the kidnapper should be discouraged until the kidnapper is convinced to surrender or is somehow lulled into easing the striker back to the base of the cartridge. Moving from .22 weapons to the 12-gauge shotgun is the other end of the spectrum. As this cartridge also has almost universal dissemination, the 12-gauge is used worldwide in homemade weapons. This cartridge is ideally suited for improvised use, as its dimensions are such that it will easily chamber into three-quarter-inch plumbing pipe. Most improvised 12-gauge shotguns utilize this pipe for