A pinfire firearm cartridge is an obsolete type of brass cartridge in which the priming compound is ignited by striking a small pin which protrudes radially from just above the base of the cartridge.
Invented by Frenchman Casimir Lefaucheaux in 1828 but not patented until 1835, it was one of the earliest practical designs of a metallic cartridge. Its history is closely associated with the development of the breechloader which replaced muzzle-loading weapons. The latter required a percussion cap, gunpowder and a projectile or charge be loaded sequentially and packed using wadding and a ramrod. By contrast pinfire cartridges were supremely convenient in that they could contain percussion cap, powder and shot in a neat pre-loaded package which was several times faster to fire and reload and was inherently safer.
Detail of a Lefaucheux M1858 pistol. Notice the pin protruding from the cartridge.The Swiss gun maker Samuel Joannes Pauly patented the first breechloading cartridge in 1812. This was for use in a shotgun with fixed barrels which was loaded by lifting a breech block on the top. French gun maker Henri Roux attempted to improve this cartridge in the 1820s but a constantly primed cartridge was felt by many to be too dangerous and many breechloading guns reverted to using an unprimed cartridge. This was fired by a separate percussion cap which was used on the still dominant muzzle-loading guns.
Casimir Lefaucheux of Paris decided in 1834 to patent a breechloader where the barrels hinged downwards to reveal the breech ends. These still used a separate percussion cap. Two years later he had the idea of reintroducing the primed cartridge for use with it. His 1836 patent was for a new type of cartridge in which the cartridge's priming compound is ignited by striking a small pin which protrudes radially from just above the base of the cartridge. These pins fitted into a small groove cut in the top of each barrel-end and made it easy to see if the gun was loaded. The cartridge used metal bases (often brass) with paper tubes which were usually home made by the shooter or his staff but were not entirely gas-tight. This reduced the force of the charge and allowed powder residue and gas to escape.
The pinfire cartridge was greatly improved by the 1846 patent (number 1963) by Houllier of Paris which introduced a base wad and effectively made the cartridge gas-tight which greatly improved the performance, and were cheap and clean shooting. These improved pinfire guns grew in popularity in France and some were imported by British gun makers to overwhelming indifference on the part of the gun users there. They were prejudiced technically against a gun that 'broke' in the middle, despite the much vaunted benefits of breechloading. They owned muzzle-loaders of exquisite perfection, considered themselves the best engineers in the world (inventing the Industrial Revolution), and had a poor view of the French - the old enemy and an unreliable ally.
It wasn't until the Great Exhibition of 1851 was held in London that breechloading guns were taken more seriously by British and American gun makers in particular. The display of a Lefaucheux breechloading gun inspired English apprentice gunmaker Edwin Charles Hodges (1831-1925) to make an improved copy and persuade leading London gun maker Joseph Lang that this was the gun of the future. Other British gun makers including Lancaster, Blanch and Reilly were similarly inspired by French originals and improved pinfire breechloaders became the new type of gun which by the end of the 1850s every fashionable British prince and titled gentleman wanted to have.
After Casimir's death in 1852, his son Eugene continued to market the pinfire design with great success. It became increasingly popular in Europe and large numbers of shotguns and revolvers (often called Lefaucheux guns after their inventor whoever the maker was), were manufactured from the mid 1850s until the 1890s. They were quicker and easier to load than percussion weapons with loose black powder, percussion caps and bullet; and they were also much more likely to fire reliably when wet. Pinfire cartridges were available in a large number of sizes for various types of weapon.
While pinfire shotguns declined from the early 1860s after the introduction of mass-produced centrefire shotgun cartridges, pinfire revolvers in particular became very successful and widespread, being adopted by the armies of France, Italy, Spain, Switzerland, Sweden and others. They were also used during the American Civil War, although sometimes despised because of their low power compared to Colt and other percussion revolvers. Some navies also adopted them, "sea service" examples often being made out of bronze which is largely unaffected by the corrosion caused by salt.
Pinfire became obsolete once reliable rimfire and centre fire cartridges became available because without a pin which needed aligning in the slot in the chamber wall they were quicker to load. They were also safer because they had no protruding pin which could cause the ammunition to accidentally detonate during rough handling, particularly of loose ammunition.
The pinfire concept was also only really suitable for single-shot or multiple-barreled firearms and revolvers as the pin would have complicated any mechanism for feeding from a magazine. Nevertheless the last practical pinfire revolvers were manufactured around 1890 but by then they were an anachronism.
Although pinfire shotgun cartridges are technically obsolete as pinfire guns have not been made in any numbers for a hundred years, enthusiasts of vintage weaponry often make pinfire cartridges from modern materials and shoot their old guns. As regards pistols, some modern novelty miniature guns are manufactured in very tiny calibres, such as 2 mm. Although not practical weapons, they use pinfire ammunition because the calibre is too small for centre fire or rimfire. Antique pinfire firearms are available, as well as specialized cartridges which can be handloaded, though the process is far more complex than for centerfire cartridges.