Which part of a firearm is primarily responsible for firing the projectile?

The trigger is the component of a firearm that is primarily responsible for firing the projectile. When the trigger is pulled, it initiates a series of mechanical actions that ultimately culminate in the firing pin striking the primer of the cartridge. This ignites the propellant, causing a rapid expansion of gases that pushes the bullet down the barrel and out of the muzzle.

It's important to understand that while other components, such as the barrel and muzzle, play essential roles in the firearm's overall function, they do not directly initiate the firing process. The barrel confines and directs the projectile, while the muzzle is simply the open end of the barrel from which the projectile exits. The stock provides stability and support to the shooter but is not involved in the firing mechanism itself. Thus, the trigger is a crucial element in enabling the firearm to discharge its projectile effectively.