A cap gun, cap pistol, or cap rifle is a toy gun that creates a loud sound simulating a gunshot and smoke when a small percussion cap is ignited. Cap guns were originally made of cast iron, but after World War II were made of zinc alloy, and most newer models are made of plastic. Cap guns get their name from the small discs of shock-sensitive explosive compounds (roughly in diameter) that provide the noise and smoke, effectively the same as the Maynard tape primer and percussion caps used in real firearms of the mid to late 1800s but usually smaller and made from cheap plastic or paper. Some are arranged in plastic rings of eight or twelve. There are also single caps, roll caps (of 50 to 500), disk caps, and cap strips all of which are actually extremely small versions of percussion fireworks. Armstrong's mixture is often used today as the explosive, but previously the tiny powder charge was a simple mixture of potassium perchlorate, sulfur, and antimony sulfide sandwiched between two paper layers that hold in the gases long enough to give a sound report when the cap is struck. Real guns that used caps first appeared around the Civil War era, when faster firing weapons were needed. The Springfield Model 1855 musket was fitted with a Maynard tape primer. A roll of paper impregnated with fulminate served as the detonator, but it was found to be impractical in wet or muddy conditions and the Union army reverted to using the conventional copper percussion cap. After the demand for caps declined, firearms companies experimented with toy cap guns modeled after real percussion cap guns. Cap guns became especially popular when the heroes of cinema and television rode through the West, ridding the territories of villains. Many cap guns were named after or endorsed by leading matinee idols like Roy Rogers, Gene Autry, Hopalong Cassidy, The Lone Ranger, Tonto, Dale Evans, Marshal Matt Dillon, or any of countless others.