bottom barrels. The .41 Rimfire bullet moved very slowly, at about , around half the speed of a modern .45 ACP. It could be seen in flight, but at very close range, such as at a casino or saloon card table, it could easily kill. There were four models with several variations. The Remington derringer design is still being made; in a variety of calibers from .22 long rifle to .45 Long Colt and .410 gauge, by several manufacturers. The current production of derringers are used by Cowboy Action Shooters as well as a concealed-carry weapon. While the classic Remington design is a single-action derringer with a hammer and tip-up action, the High Standard D-100 introduced in 1962, is a hammer-less, double-action derringer with a half-trigger-guard and a standard break action design. These double-barrel derringers were chambered for .22 Long Rifle and .22 Magnum and were available in blued, nickel, silver, and gold plated finishes. Although, they were discontinued in 1984, American Derringer would obtain the High Standard design in 1990 and produce a larger .38 Special version. These derringers called the DS22 and DA38 are still being made and are popular concealed carry handguns. The COP .357 is a modern 4-shot Derringer-type pistol chambered for .357 Magnum. Introduced in 1983, it is a double-action weapon about twice as wide, and substantially heavier than the typical .25 automatic pistol. Still, it is relatively compact size and a powerful cartridge makes it an effective defensive weapon or a police backup gun. The COP .357 is quite robust in design and construction. It is made of solid stainless steel components. Cartridges are loaded into the four separate chambers by sliding a latch that "pops-up" the barrel for loading purposes, similar to top-break shotguns. Each of the four chambers has its own dedicated firing pin. It uses an internal hammer, which is activated by depressing the trigger to hit a ratcheting/rotating striker that in turn strikes one firing pin at a time. Older "pepperboxes" also used multiple barrels, but the barrels were the part that rotated. The COP .357 operates similarly to the Sharps derringer of the 1850s, in that it uses the ratcheting/rotating striker, which is completely internal, to fire each chamber in sequence. Semi-automatic pistols In 1896, Paul Mauser introduced the Mauser C96, the first mass-produced and commercially successful semi-automatic pistol, which uses the recoil energy of one shot to reload