When the .50 caliber (12.7mm) sniper rifle was introduced in the 1980s, it was expected that records for the longest range sniper shot would regularly be broken. That finally happened, in Afghanistan on March 2-1, 2002. A team of Canadian snipers (Master Corporal Graham Ragsdale, Master Corporal Arron Perry and Corporal Dennis Eason of Princess Patricia's Canadian Light Infantry), using the .50 caliber MacMillan Tac-50 sniper rifle, got at least one kill at 2,400 meters. There were several others at ranges nearly as long.
The previous record had been 2,250 meters, set by U.S. Marine Gunnery Sgt. Carlos Hathcock in Duc Pho, South Vietnam in 1967. The Hathcock shot was also made with a .50 caliber weapon, but this was not the modern .50 caliber sniper rifle, but a standard M-1 .50 caliber machine-gun with a scope on it. The previous records, many with poor documentation, with 7.62mm caliber sniper rifles, rarely exceeded a thousand meters. Technically, the 12.7mm sniper rifle is only accurate enough for consistent hits at up to about 1,800 meters.
The Canadians, and all modern snipers, use custom built rifles and ammo for their work. Hathcock had another disadvantage, he was firing in hot and humid Vietnam, while the Canadians were firing in the thin (at 11,000 feet) and cold air of Afghanistan. The hot, humid lowland air provides more resistance, and distortion, for a bullet. With that in mind, Hathcock always insisted that the shot was as much luck as skill. The Canadian shots were all skill, as they killed nearly two dozen Taliban and al Qaeda fighters at ranges of around 2,000 meters.
Before the specially made .50 caliber sniper rifles came along, the standard sniper rifle was 7.62mm (.30 caliber), with a standard effective range of 800 meters (although shots out to 1,000 meters were not unknown). The .50 caliber sniper rifle doubled those ranges, and then some. U.S. troops in Iraq are using .50 caliber sniper rifles, but are not getting as much opportunity to make really long distance shots because most of the operations are in flat areas.