What part of a firearm does a projectile travel through?

The correct choice is the barrel, which is the component of a firearm through which the projectile travels after being fired. When a bullet is discharged, it is propelled down the barrel by the expanding gases created from the ignited gunpowder in the cartridge. The barrel is designed to guide the projectile and help stabilize its flight, often featuring rifling (spiral grooves) that spins the bullet for increased accuracy.

The bore refers specifically to the interior diameter of the barrel—it is where the projectile travels but does not account for the entire system of guiding and propelling the bullet. The stock is the part of the firearm that is held against the shoulder, providing stability and support, while the receiver houses the firearm's operating components, such as the trigger and firing mechanism, but it does not guide the projectile itself. Hence, the barrel is the essential part that directly facilitates the projectile's movement.