Flash pan

Flash pans are found on gonnes, matchlocks, wheellocks, snaplocks, snaphances, and flintlocks.

A small amount of finely ground gunpowder is placed in the flash pan and ignited.

The flash of flame travels through the touch hole igniting the main charge of propellant inside the barrel.

The ignition of the main charge from the flash pan was not a guaranteed operation, however, and sometimes it failed.

This led by the end of the 17th century to the expression "flash in the pan" to mean a failure after a brief and showy start, or momentary sensation of no real importance.