Barrel
The rifled tube that contains the burning charge, spins the bullet, and aims it. Its bore, twist, and crown set the ceiling on a rifle's accuracy.
The barrel is where everything ballistic happens. Powder burns at the chamber end, pressure drives the bullet up the bore, and the rifling spins it for stability while the twist rate decides which bullet weights it can hold. The bullet leaves at the crown, whose evenness controls how cleanly it lets go.
Barrel profile trades weight against stiffness and heat. A heavy bull barrel resists vibration and holds zero through a long string, while a fluted barrel sheds some of that weight without losing all the rigidity. For precision, a quality barrel is the component that most directly delivers accuracy.