 Before this development, firearms used flintlock ignition systems that produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the gun's main powder charge (the flintlock mechanism replaced older ignition systems such as the matchlock and wheellock).Flintlocks were prone to misfire in wet weather, and many flintlock firearms were later converted to the more reliable percussion system.The percussion cap is a small cylinder of copper or brass with one closed end.