Sniper rifles have some distinctive features which separate them form other normal rifles and weapons.
The single most important characteristic that sets a sniper rifle apart from other military or police small arms is the mounting of a telescopic sight, which is relatively easy to distinguish from smaller optical aiming devices found on some modern assault rifles and submachine guns. This also allows the user to see farther. The telescopic sights used on sniper rifles differ from other optical sights in that they offer much greater magnification (more than 4× and up to 40×), and have a much larger objective lens (40 to 50 mm in diameter) for a brighter image. Most telescopic lenses employed in military or police roles have special reticles to aid with judgment of distance, which is an important factor in accurate shot placement due to the bullet's trajectory.