Just breathing and a slight flinch can cause you to be way off the mark at 300, not to mention wind
Just imagine how calm these fella's were when they squeezed the trigger and all the other factors that were involved.



August 7, 2002; A Canadian sniper in Afghanistan has been confirmed as hitting an enemy soldier at a range of 2,310 meters, the longest recorded and confirmed sniper shot in history. The previous record of 2,250 meters was set by US Marine sniper Carlos Hathcock in Vietnam in 1967. The Canadian sniper was at an altitude of 8,500 feet and the target, across a valley, was at 9,000 feet. Canadian sniper units often operated in support of US infantry units, which were grateful for their help. The record lasted only one day, until a second Canadian sniper hit an enemy soldier at 2,400 meters. The Canadian snipers were firing special ..50-caliber McMillan tactical rifles, which are bolt-action weapons with five-round magazines. The Canadian snipers were the only Canadian troops operating without helmets or flak jackets as they had too much other equipment to carry. Each three-man team had one sniper rifle, three standard rifles (Canadian C7s), one of them with a 203mm grenade launcher.