"One shot, one kill" is the sniper motto, and this can only be accomplished with the help of heavily modified rifles, with hollow wood or fiberglass handles, upgraded trigger mechanisms and high-power optical telescopes.

But what is the most powerful sniper rifle in the world? Without a doubt, it's the Barrett M107 Sniper Rifle, the most impressive of its kind ever built. Probably the most technologically advanced sniper rifle in the world, it is primarily used by US troops engaged in some of the bloodiest conflicts in the world.

The high-powered sniper rifle used by the U.S. military - the M107 rifle (formerly the M82) - was first used by American forces in Operation Desert Storm. It was built by an independent contractor, the Barrett Firearms Company, and its owner, Ronnie Barrett, is only the fourth individual to design a weapon to be used by the US Army.

The M107 .50-caliber long-range rifle is semi-automatic and is being fielded to infantry soldiers. It can engage targets to 2,000 meters with precision. At 29 inches long, the frame mounted, bolt-action XM107 weighs 28.5 pounds with optics.

It fires one of the most powerful rounds in the world, the .50 Browning Machine Gun (12.7 × 99 mm NATO) or .50 BMG cartridge. The bullet is .511 in (12.98 mm) in diameter and 5.45 in (138.43 mm) in overall length, which makes the 5.56 NATO caliber or the 7.62 one used in AK-47s look like a firecracker.

A well trained sniper can hit a 5 in (12 cm) target at a distance of 2 kilometers (1.5 mi) and there are reports of US snipers successfully taking out insurgents in Afghanistan from 2,430 meters (1.8 mi) away.

The bullet can pass through 3 cm (1.2 in) of armor plating, the standard for most light-armored vehicles, and more that a foot-thick wall, behind which most enemies in Iraq and Afghanistan feel pretty safe. It is mostly used against targets like radar cabins, trucks, parked aircraft and so on, but it's also used against human threats, like enemy snipers, mortar crews and machine gun pillboxes.

The rifle itself is 115 or 122 cm (48 or 57 inches) in length, depending on the handle, and although it's a giant, its recoil has been reduced by 70 percent compared to other high-caliber rifles, so it's relatively easy to operate, and weighs only 31 lb (13.6 kg).

But the most impressive characteristic of this monster of a riffle is the fear factor. The bullet - traveling at Mach 1.5 up to Mach 3 - makes it silent and effective, so the target drops dead a few seconds before the actual sound of the shot is heard. And the fact that it can fire all the ten rounds in the magazine in less than 10 seconds means that a small platoon of enemies is dead almost before they can hear the shots.

That's more than enough to make it one of the most dreaded weapons on the battlefield.