Percussion Cap - History

History

The percussion cap replaced the flint, the steel "frizzen", and the powder pan of the flint-lock mechanism. It was only generally applied to the British military musket (the Brown Bess) in 1842, a quarter of a century after the invention of percussion powder and after an elaborate government test at Woolwich in 1834. The first percussion firearm produced for the US military was the percussion carbine version (c.1833) of the M1819 Hall rifle.

The discovery of fulminates was made by Edward Charles Howard (1774–1816) in 1800. The invention that made the percussion cap possible using the recently discovered fulminates was patented by the Rev. Alexander John Forsyth of Belhelvie, Aberdeenshire, Scotland in 1807.

It consisted of priming with a fulminating powder made of fulminate of mercury, chlorate of potash, sulphur, and charcoal, which was exploded by concussion. It was an invention born of necessity: Rev. Forsyth had noticed that sitting birds would startle when smoke puffed from the powder pan of his flintlock shotgun, giving them sufficient warning to escape the shot. His invention of a fulminate-primed firing mechanism deprived the birds of their early warning system, both by avoiding the initial puff of smoke from the flintlock powder pan, as well as shortening the interval between the trigger pull and the shot leaving the muzzle.

Fulminate-primed guns were also less likely to misfire than flintlock guns. However, it was not until after Forsyth's patents expired that the conventional percussion cap system was developed. The percussion cap helped lead to the Self Contained Cartridge, where the bullet is held in by the casing, the casing is filled with gun powder, and a primer, is at the end.

Joshua Shaw, an English-born American, is sometimes credited with the development of the first metallic percussion cap in 1814, but his claim remains clouded with controversy as he did not patent the idea until 1822. Shaw's percussion caps used a mixture of fulminate of mercury, chlorate of potash, and ground glass contained in a small metallic cup. Other possible claimants include François Prélat, who patented the percussion cap in 1818, Joseph Manton, Col. Peter Hawker, and most likely of all, Joseph Egg (nephew of Durs Egg).

This invention was gradually improved, and came to be used, first in a steel cap, and then in a copper cap, by various gunmakers and private individuals before coming into general military use nearly thirty years later.

The alteration of the military flintlock to the percussion musket was easily accomplished by replacing the powder pan and steel "frizzen" with a nipple, and by replacing the cock or hammer which held the flint by a smaller hammer formed with a hollow made to fit around the nipple when released by the trigger. On the nipple was placed the copper cap containing the detonating composition, now made of three parts of chlorate of potash, two of fulminate of mercury and one of powdered glass. The hollow in the hammer contained the fragments of the cap if it fragmented, reducing the risk of injury to the firer's eyes.

The detonating cap, thus invented and adopted, brought about the invention of the modern cartridge case, and rendered possible the general adoption of the breech-loading principle for all varieties of rifles, shotguns and pistols.

Caps are used in cartridges, grenades, rocket-propelled grenades, and rescue flares. Percussion caps are also used in land mine fuzes, boobytrap firing devices and anti-handling devices.