The
frizzen, historically called the
steel, is an "L" shaped piece of steel hinged at the rear used in
flintlock firearms. It is positioned over the
flash pan so as to enclose a small priming charge of
black powder next to the flash hole that is drilled through the barrel into where the main charge is loaded. When the trigger is pulled, the hammer or cock—which includes a shaped piece of
flint held into a set of jaws by a scrap of leather or thin piece of lead—snaps forward causing the flint to scrape down the face of the frizzen (historically called the 'battery'), throwing it back to expose the black powder in the pan. The flint scraping the steel causes a shower of sparks to be thrown into the pan, igniting the black powder and sending flames through the
touch hole, which in turn ignites the main charge of black powder in the
breech of the barrel, shooting the projectile out the barrel.