Pipes. Plumbers, and Other Spare Parts • 35 clever handmade antique firing device is a double-barreled •22-caliber weapon used for close-quarter mayhem. (Courtesy of Alex Foley.) ^ber zip gun firing a keyholed bullet. One police officer said, 'Those keyhole .22 slugs are dangerous as hell, even out of a street-crude zip gun. I'd sooner face a drunk with a standard piece than some