The main tool of such a specialist - a rifle with a powerful optical sight. Modern optics allows you to "hit the apple" from a distance of several kilometers. However, it is not limited to a good sight. We can not ignore the external factors, such as the direction and strength of the wind, humidity, gravity of the Earth and even its rotation.
History knows a lot of extremely accurate long-range shots. However, today the world record belongs to Russian snipers. They managed to hit the target at a distance of almost 3500 meters.