Real guns that used caps first appeared around the United States Civil War era, when faster firing weapons were needed.
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.
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.
The "Golden Age" of cap guns was roughly a 20-year period following World War II when television became popular and such companies as Nichols, Hubley, Kenton, Kilgore, Wyandotte, Classy, Mattel, Actoy, Esquire, George Schmidt, and J & E Stevens in the US and companies like Lone Star Toys in the UK made millions of cap guns in various versions.
One of the last famous ones to sell widely was a toy rifle named after the television show, The Rifleman, which aired from 1958 through early 1963.
Pulling back on a slide, which simulated the charging handle of the real Thompson, prepared the gun for firing by tensioning a spring.
When the trigger was pulled the spring power would drive the mechanism, firing a series of up to ten caps from a sprocket-fed roll.
Due to the low energy contained in a paper cap and the poor seal around the cartridge, these spud guns usually have very modest range, barely enough to eject the potato cutting.
This mechanism was triggered by drawing the figure's spring-loaded right arm back and releasing it to swing forward; the explosion of the cap was intended to simulate a thunderous noise caused by the superhuman power of the character's punch.
A relatively new type of Airsoft, known as hybrid guns, use small round BBs in the tip of a casing, usually designed to mimic that of its respective magazine.
In electric models, the caps are burst, and the pressure is used to propel the BB forward in a manner similar to real firearms.
Tri-ang Railways in the UK utilised caps in some of their OO gauge range of model rolling stock and accessories for toy play effect in the 1960s such as an exploding box car, a detonating rocket on their carrier transporter and an exploding fog signal accessory to mimic the effect of track detonators.