What happens when the primer is struck by the firing pin?

When the primer is struck by the firing pin, it ignites and creates a flame. This ignition occurs due to the sensitive composition of the primer, which generally contains a mix of chemicals designed to produce a quick and intense reaction when struck. This flame produced by the ignited primer then travels through the flash hole into the main body of the cartridge, igniting the gunpowder. The rapid combustion of the gunpowder generates high-pressure gas, which ultimately drives the bullet down the barrel and out of the firearm.

Understanding this process is crucial in firearm operation, as it highlights the critical role that the primer plays in the firing sequence. The other options do not accurately represent the immediate consequences of the firing pin's action on the primer; thus, focusing on the ignition process clarifies the pathway from pulling the trigger to firing the bullet.