One thing I enjoy about the Web is how you can look up one specific thing, then begin following links and end up somewhere you never would’ve gone directly.
One of those places is the Wikipedia article about the .50 calibre Browning Machine Gun cartridge. Though it was first used in 1921, the cartridge is still in use today. It was designed for use in machine guns, but it’s also used in sniper rifles. The longer the bullet is in the air, the more it can be affected by the movement of the air it is travelling through. A heavier bullet will minimize this interference.
The bullet itself is 13 mm (0.510″) in diameter but the cartridge is 20.5 mm (0.804″) in diameter at its widest point. The cartridge is also 138 mm (5.45″) long. I can’t imagine a cartridge nearly an inch in diameter and six inches long being used in a rifle. But it gets worse. The Browning M2 .50 calibre machine gun uses the same cartridge and can fire more than 800 rounds per minute. Aircraft mounted M2 guns with electric feed mechanisms can fire 1200 rounds per minute. That’s 20 per second, for goodness sakes.
That’s putting an incredible volume of metal into the air, but when accuracy counts, it’s strictly one bullet at a time.
In 2002, an extremely skilled gentleman named Rob Furlong used a McMillan Tac-50 sniper rifle and a .50 BMG cartridge to break a record. Furlong was a Corporal with the Princess Patricia’s Canadian Light Infantry stationed in Afghanistan. What he did was kill an enemy combatant at a distance of 2430 meters (7971 feet).
Talk about reaching out to touch someone.
What makes this all the more remarkable is that the muzzle velocity for the .50 BMG is in the 800–900 metres per second range, depending on the exact ammunition and weapon used. Even ignoring the bullet’s reduction in speed due to air resistance, Corporal Furlong’s record shot reached the target three seconds after he pulled the trigger! Given acceleration due to gravity, the bullet would have dropped about 45 metres because of the Earth’s pull in the three seconds it was in the air. Furlong had to account for this when aiming.
Even worse is the annoying habit people have of moving around. He had to know where his target would be three seconds in the future.
I used the three linked Wikipedia articles as source material for this entry.