the increased capability for concealment. DA and DAO revolvers were the standard-issue sidearm of countless police departments for many decades. Only in the 1980s and 1990s did the semiautomatic pistol begin to make serious inroads after the advent of safe actions. The reasons for these choices are the modes of carry and use. Double action is good for high-stress situations because it allows a mode of carry in which "draw and pull the trigger" is the only requirement—no safety catch release nor separate cocking stroke is required. Other In the cap-and-ball days of the mid 19th century, two revolver models, the English Tranter and the American Savage "Figure Eight", used a method whereby the hammer was cocked by the shooter's middle finger pulling on a second trigger below the main trigger. Iver Johnson made an unusual model from 1940 to 1947 called the Trigger Cocking Double Action. If the hammer was down, pulling the trigger would cock the hammer. If the trigger was pulled with the hammer cocked, it would then fire. This meant that to fire the revolver from a hammer down state, the trigger must be pulled twice. This is close from the action of the "sytème Triple action" patented by frenchman Eugène Lefaucheux in 1862 for pinfire revolvers produced in the 1860's in France. The Lefaucheux Triple Action can be used in single action by cocking the hammer with the thumb, or in double action with a long pull on the trigger, or the hammer can be cock by a pull on the trigger, allowing then to shoot in single action. French patent number 55784, 27th Sept. 1862 to Eugène Lefaucheux. 3D printed revolver The Zig zag revolver is a 3D printed .38 Revolver made public in May 2014. It was created by a $500 3D-printer using plastic filament, but the name of the printer was not revealed by the creator. It was created by a Japanese citizen from Kawasaki named Yoshitomo Imura. He was arrested in May 2014 after he had posted a video online of himself firing a 3D printed Zig Zag revolver. It is the first 3D printed Japanese gun in the world which can discharge live cartridges. Use with suppressors As a general rule, revolvers cannot be effective with a sound suppressor ("silencer"), as there is usually a small gap between the revolving cylinder and the barrel which a bullet must traverse or