Before firing, the percussion lock is equipped with an impact-sensitive ignition charge (usually a percussion cap ). When the trigger is pulled, a cock, which is cocked before the shot, strikes the ignition charge, which then ignites the propellant charge , whereupon the shot breaks.
The forerunner of the percussion lock was the flint lock, the basic construction of which was taken over by the percussion lock.
One of the earliest designs of a percussion lock comes from Alexander John Forsyth , who had his design patented in 1807. Instead of a primer, this lock had a horizontally rotatable magazine with impact-sensitive explosive. With each turn, a certain amount of powder entered the ignition pan and was ignited when the shot was released by the tap.
In later designs, ignition platelets or capsules in the form of pellets, pills, or paper strips were used.
In the years 1814 to 1816, several inventors patented copper primers, which are mainly used in the percussion weapons that are still used today in sport and traditional shooting. These primers are placed on a hollow piston before the shot and ignited when the hammer is turned off.
The percussion lock is less sensitive to the weather and generally failed less often than its predecessor. That is why it quickly caught on in military and civilian weapons. It was in turn replaced by the needle gun from the middle of the 19th century .
An elementary advantage of the percussion lock is the lack of a flash of light from the previous charge in the flintlock pan when firing. Since many closed their eyes when shooting, they deviated slightly from the target. In addition, there was a higher pressure in the barrel compared to flintlock weapons, since with these a small part of the pressure escaped through the ignition hole. Higher pressure resulted in greater reach and precision.
After the introduction of the primer, infantry units quickly achieved higher hit rates. The new technology was decisive for battle and war.