The flash pan or priming pan is a small receptacle for priming powder, found next to the touch hole on muzzleloading guns. Flash pans are found on gonnes, matchlocks, wheellocks, snaplocks, snaphances, and flintlocks.
The flash pan was at first attached to the gun barrel, but was later moved to the lock plate of the gun. 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. Unlike cannon, it was not necessary (or desirable) to place priming in the touch hole itself. The flash alone, and not particles of burning powder was enough to ignite the main charge.