Frizzen

When the trigger is pulled, the cock, which holds a shaped piece of flint clamped in a set of jaws with a scrap of leather or thin piece of lead, snaps forward causing the flint to scrape downward along the frizzen's face (historically called the 'battery'), throwing it forward into the open position and exposing the priming powder.

The development of the frizzen which combines both the "battery" or striking surface and separate pan cover on the less advanced "snaphaunce" lock is often credited to French gun maker Marin le Bourgeoys around 1610.

It is important that the metal of the frizzen be brought to a sufficiently high carbon content by the process of carburization, wherein carbonaceous materials such as horn, hooves, and leather scraps were wrapped around the frizzen in a clay or metallic crucible which was then placed into a forge or other furnace for several hours to raise the carbon content of the steel through the process of diffusion.

This process increases the carbon content of the iron in a layer close to the surface of the frizzen so that it hardens the outside while the center remains relatively ductile so as to prevent through-cracking.

Through the wear of continued use a frizzen will lose its ability to create enough sparks to reliably ignite the powder, thereby necessitating that it be re-hardened or replaced.