What is the primary purpose of rifling in a firearm's barrel?

Rifling in a firearm's barrel refers to the helical grooves cut into the interior of the barrel. This design is crucial for imparting a spin to the bullet as it travels through the barrel and exits into the air. The primary purpose of rifling is to stabilize the bullet’s flight by creating a gyroscopic effect. This stabilization is essential for accuracy, as it helps the bullet maintain a straight trajectory over longer distances, reducing the impact of air resistance and external factors that could deflect it off course.

While enhancing magazine capacity, improving bullet speed, and reducing recoil are important aspects of firearm design and function, they do not directly relate to the primary role of rifling. Magazine capacity deals with how many rounds a firearm can hold, bullet speed is influenced by other factors like powder load and barrel length, and recoil is typically managed by the firearm's design and other components rather than the rifling itself. Therefore, the correct answer emphasizes the critical role of rifling in ensuring that bullets fly accurately and effectively towards their target.