U.S. commandos test new 5.56 mm dim tracer ammo.

U.S. Army special warfare units are considering buying a new type of armor-piercing tracer ammunition that makes it possible for sharpshooters--using night-vision rifle sights--to fire their weapons at night and not be dazzled by the muzzle flash.

Tracer ammunition uses a bullet that contains a pyrotechnic composition--similar to that used in a flare--in a hollow base, which is ignited by the cartridge powder when fired.

It is used mostly by military units for target spotting and marksmanship training, because it allows the shooter to see the bullet's trajectory.

Standard tracer ammunition creates excessive illumination or visual interference--known as blooming effect--for the user, when viewed through night-vision devices.

Infrared tracer, also called dim-tracer ammunition, has a special cartridge, which is invisible to the naked eye, but is visible through night-vision devices and does not cause the blooming effect.

Dim-tracer ammunition has been around for several years, but it's been only recently that 5.56 mm, NATO-compliant armor-piercing rounds have been available to military buyers. The infrared tracer is loaded with a special powder that reduces the muzzle flash and minimizes the signature that can expose the gunner to the enemy.

About two years ago, the Nordic Ammunition Company (Nammo) introduced a 5.56 mm, dim-tracer projectile that meets NATO requirements. The round can penetrate 15 mm armor and any Kevlar helmet or vest from a distance of 100 meters.

Ever since, the company has been trying to garner international sales of this ammo, which has a tungsten core and a steel jacket, said Mart Pella, marketing manager at Nammo corporate headquarters, in Sweden. He said that U.S. Army special-operations units are now testing the 5.56 mm dim-tracer rounds and possibly could acquire the ammunition for operational use. Sweden's special forces so far are the only buyers of this round.

The U.S. government, however, is Nammo's biggest customer.

Projectiles that have a steel core tend to be more penetrating, but Nammo decided to use tungsten, because it has "better density," Pella explained.

"For future night combat, the conventional tracer must be replaced or complemented with a tracer cartridge that is not visible to the human eye, is visible with image intensifiers and creates minimal muzzle flash," he said. "A sniper can aim the target and see it without being blinded by blooming." Further, if the enemy does not have night-vision goggles, he cannot see where the fire is coming from--and he will not know where to hide.

International small-arms expert Terry Gander said that Nammo is probably the only company that has the 5.56 mm dim-tracer bullet. But he noted that the 5.56 mm size is not the preferred sniper cartridge. "They usually go for 7.62 mm," Gander said.

Other experts noted that, because the Nammo dim tracer still is an unproven technology, it's not clear what effects it may have on shooting accuracy and long-term barrel wear.