Canadian Firearms Safety Course (CFSC) Practice Exam

The component that strikes and ignites the primer in a percussion cap is the hammer. The hammer is a crucial part of the firearm's firing mechanism. When the trigger is pulled, the hammer moves forward with force and strikes the percussion cap located on the nipple of the firearm. This impact causes a chemical reaction in the primer material, resulting in ignition.

The trigger is responsible for initiating this action but does not directly ignite the primer. The nipple serves as a mounting point for the percussion cap, and the barrel functions as the chamber through which the bullet is fired, playing no direct role in the ignition process. Therefore, the hammer directly sets off the firing sequence when it strikes the cap, making it the correct component in this context.