What happens immediately after the firing pin strikes the primer in a rifle?

When the firing pin strikes the primer of a cartridge, the primer is designed to ignite upon impact. This initiation causes a small explosion, resulting in the primer producing a spark. The spark then ignites the gunpowder inside the cartridge, which generates gas and pressure, ultimately propelling the bullet through the barrel.

The sequence of this action is critical in understanding how a firearm operates. Once the primer is struck, it is the chemical reaction initiated by the primer that plays the pivotal role in firing the bullet. The bullet does not leave the barrel until after the gunpowder has been ignited and has built enough pressure to act on the bullet.

Other options do not accurately reflect what occurs immediately after the firing pin strikes the primer. The bullet is not expelled from the barrel until the gunpowder ignites, resetting the trigger happens after the shot is fired and typically occurs in semi-automatic or automatic firearms, and automatic reloading is not a function associated with the firing pin's action but rather with the firearm's overall mechanism.