Which part of a firearm is responsible for firing the cartridge?

The firing pin is the critical component in a firearm that directly initiates the firing of a cartridge. When the trigger is pulled, it activates the mechanism that releases the firing pin. The firing pin then strikes the primer of the cartridge, igniting the propellant within. This ignition results in the rapid expansion of gases that propel the bullet down the barrel.

Understanding the function of the firing pin is essential, as it is the point of contact that transforms the action of pulling the trigger into a ballistic event. It is important to note that without a properly functioning firing pin, even if the trigger and other components are functioning correctly, the firearm will not be able to fire.