What does rifling cause the bullet to do as it travels in the barrel after being fired?

Rifling in a firearm's barrel refers to the helical grooves cut into the inside of the barrel. These grooves impart a spin to the bullet as it travels down the barrel after being fired. This spinning motion stabilizes the bullet during its flight, allowing it to maintain a straight trajectory and improving accuracy. The gyroscopic effect created by the spin helps the bullet resist external forces such as wind and gravity.

The other options do not accurately describe the effects of rifling. For example, bouncing off the sides of the barrel would indicate a lack of control and could lead to erratic bullet paths, which contradicts the purpose of rifling. Rapid acceleration is primarily a function of the explosive force from the gunpowder igniting, not directly tied to rifling. Finally, while some bullets may expand upon exiting the barrel due to design features — such as hollow points — this is not a direct result of rifling. Thus, the primary and intended effect of rifling is to spin the bullet for stabilization and accuracy.