How wheellock weapons worked

Early firearms worked by the direct application of heat to gunpowder, an operation that was clearly fraught with danger, especially as this took place a few inches in front of the gunman’s face. The earliest such weapons used the “matchlock” system, in which the heat was supplied by a naked flame in the form of a smouldering piece of cord brought into direct contact with gunpowder in an open pan, a process that was not only dangerous but unreliable. The way forward was to use friction as the heat source, and the first method to do so was the wheellock, which was used on weapons from around 1550 to 1650, although weapons from both before and after these dates can be found.

The idea of the wheellock was a simple one, although the mechanism was quite complicated, and later versions of muskets and pistols developed in various directions. What is described here is the fundamental operating principle of the wheellock.

The wheel was made of steel, with a roughened edge, set on a square spindle. The edge of the wheel, which was set vertically to the stock of the weapon, met the pan beside the touchhole that conveyed heat to the main charge inside the barrel. The wheel was also linked to a powerful V-spring.

Another vital part of the mechanism was a metal arm that held in its jaws a piece of pyrites, a commonly found mineral which was renowned for its ability to strike sparks when in contact with steel. Indeed, the word derives from the Greek for “fire”.

In order to fire a wheellock weapon, the wheel needed to be wound against the spring, which was done by fitting a key to the square spindle and turning it until the spring was fully compressed. The wheel would then be held in place by a “sear”, a small arm that engaged with a hole in the side of the wheel, thus locking it in place. The piece of pyrites then had to be placed against the edge of the wheel and held firmly against it by a ratchet device of some kind. Finally, after a pinch of powder was placed in the pan, the weapon was ready to be fired.

The action of pulling the trigger withdrew the sear from the wheel, causing it to spin rapidly as the pressure of the spring took over. The rubbing of the wheel against the pyrites produced sparks which, when they reached the pan, ignited the powder.

The gunman would then have to reload the weapon and pull the pyrites away from the wheel before repeating the process for the next shot. All in all, it was not a notably faster process than that required for operating a matchlock weapon, but it was somewhat safer and was not as reliant on good weather conditions, given that less powder was needed to prime it and there was therefore less chance of it getting wet or being blown out of the pan by the wind. There was also less risk of a “flash in the pan”, meaning the burning of the powder in the pan without a subsequent firing of the main charge, caused by the touchhole being blocked or the powder trail not being complete.

Despite the advantages of the wheellock, it was expensive to produce and tended to be used more for hunting by aristocrats than by armies in the field.

The army soldier had to make do with matchlock weapons for many years after wheellock mechanisms were available. Not only were matchlocks cheaper and less complex, with less to go wrong in terms of their mechanical operation, but their operators were more dispensable, the safety of the common soldier not being a prime consideration.

The wheellock did, however, make possible the development of personal weapons in the form of pistols, which would have been quite impractical under the matchlock system. Again, pistols were the property of rich people, and many became prized possessions with gunsmiths encouraged to produce highly ornate pieces, with inlays of ivory, gold and silver on the stocks.

The real successor to the matchlock was, therefore, not the wheellock but the simpler, and therefore more enduring, flintlock.