The SwissMiniGun company of La Chaux-de-Fonds, Switzerland, has developed the SwissMiniGun C1ST, which is a double-action .09 caliber six-shooter that's just over two inches long and weighs 0.7 oz.
Despite much interest from gun collectors, the SwissMiniGun is not importable into the U.S. -- the U.S. Department of Justice has said that the miniature revolver does not meet with the minimum size prerequisites.
Photo courtesy of SwissMiniGuns
