What term describes the grooves in the metal of a firearm barrel that make the bullet spin?

The term that describes the grooves in the metal of a firearm barrel that make the bullet spin is rifling. This is an essential feature of many modern firearms, as the specific pattern of grooves inside the barrel imparts a stabilizing spin to the bullet as it travels down the barrel and exits into the air. This spinning motion helps the bullet maintain a straighter trajectory and improves its accuracy over distances.

Bore refers to the interior diameter of the firearm barrel and does not encompass the grooves themselves. Choke refers to a feature in shotgun barrels that constricts the shot's spread after it exits the barrel, impacting shot patterns rather than the bullet's spin. Gauge is a measurement that denotes the bore size of shotguns, with larger numbers indicating a smaller bore diameter, which does not relate to the mechanics of spinning the bullet. Understanding these distinct definitions helps clarify why rifling is the correct term for the grooves in the barrel that enhance a bullet's flight characteristics.