Semi-automatic rifles are self-loading rifles. While they can vary greatly in form and functionality, they all have one thing in common. These types of guns uses gas or recoil energy to eject the spent shell and a new round is chambered from the magazine. This allows another bullet to fire when the shooter pulls the trigger again. Most also have rifled barrels, which means that there are grooves lengthwise across the inside of the barrel. When the bullet fires through the barrel, these grooves cause the bullet to spin, allowing it to travel at a greater velocity and enhancing accuracy.
These types of firearms are popular for use in sport shooting, hunting, and for self-defense.