What part of a firearm directs the projectile out of the barrel?

The correct answer is the muzzle, which is the end of the barrel of a firearm where the projectile exits when fired. The muzzle plays a critical role in directing the projectile; as the ammunition is ignited, the expanding gases push the bullet out of the barrel at high speed. The design of the muzzle affects the accuracy and velocity of the projectile, making it a key component of a firearm's overall performance.

In contrast, the sight is used for aiming and has no role in directing the projectile. The breech refers to the rear part of the barrel where the cartridge is inserted, and while it is essential for the loading process, it does not influence the direction of the projectile's flight. The chamber is the specific compartment within the breech where the cartridge sits before firing. While the chamber holds the cartridge in place, similar to the breech, it does not dictate how the projectile is directed once it is discharged.