U.S. Marine sniper Carlos Hathcock in 1967 during the Vietnam War, at a distance of ; Hathcock used the .50 BMG in an M2 Machine Gun equipped with a telescopic sight. This weapon was used by other snipers, and eventually purpose-built sniper rifles were developed specifically for this round. In June 2017, a McMillan Tac-50 was used by a sniper with Canada's Joint Task Force 2 to kill an Islamic State insurgent in Iraq, setting the new world record for the longest confirmed kill shot in military history at . Before that, a British sniper in Afghanistan held the record at using a .338 Lapua Magnum (8.58×70 mm) rifle. In addition to long-range and anti-materiel, the U.S. military uses .50 BMG weapons to detonate unexploded ordnance from a safe distance. It can disable most unarmored and lightly armored vehicles. Some civilians use .50 caliber rifles for long-range target shooting: the US-based Fifty Caliber Shooters Association holds .50 BMG shooting matches. Power A common method for understanding the actual power of a cartridge is comparison of muzzle energies. The .30-06 Springfield, the standard caliber for American soldiers in both World Wars and a popular caliber amongst American hunters, can produce muzzle energies between . The .50 BMG round can produce between , depending on its powder and bullet type, as well as the weapon it is fired from. Due to the high ballistic coefficient of the bullet, the .50 BMG's trajectory also suffers less "drift" from cross-winds than smaller and lighter calibers, making the .50 BMG a good choice for high-powered sniper rifles. Cartridge dimensions The .50 BMG (12.7×99mm NATO) cartridge has a capacity of . The round is a scaled-up version of the .30-06 Springfield but uses a case wall with a long taper to facilitate feeding and extraction in various weapons. The common rifling twist rate for this cartridge is 1 in , with eight lands and grooves. The primer type specified for this ammunition is a boxer primer that has a single centralized ignition point (US and NATO countries). However, some other countries produce the ammunition with Berdan primers that have two flash holes. The average chamber pressure in this round as listed in TM43-0001-27, the U.S. Army Ammunition Data Sheets — Small Caliber Ammunition, not including plastic practice, short cased spotter, or proof/test loads, is . The proof/test pressure is listed as . Military cartridge types The