Rifle ammunition consists of a cartridge that contains a bullet, gunpowder, and a primer. The bullet is the projectile that is fired from the rifle, while the gunpowder ignites when the primer is struck, creating gas that propels the bullet down the barrel. Rifle ammunition comes in various calibers, which refer to the diameter of the bullet. Common calibers include .223 Remington, .308 Winchester, and .30-06 Springfield. Each caliber is designed for specific purposes, such as hunting, target shooting, or military use, and can vary in terms of velocity and energy.