August 10, 2012: For two years now the U.S. Army has been using the new lead-free M855A1 5.56mm round in Afghanistan. The new round is more expensive and marginally better than the older M855. The major reason for the appearance of the M855A1 was years of political pressure on the army to use non-lead bullets. That came about because training and combat use of army 5.56mm weapons puts 2,000 tons of lead back into the environment each year. This lead was originally taken out of the environment to be temporarily stored in the form of bullets. The lead is also contained in a copper jacket and most of it stays that way. That's probably why no environmental study has ever found lead leaching out of spent bullets and getting into anyone's water. But just the thought of all those billions of lead bullets lying in the ground mobilized an international movement to ban lead bullets.
Fortunately the M855A1 was also about several other improvements besides being lead-free. For example, the M855A1 is a little more accurate at longer ranges. This is important in a place like Afghanistan. The M855A1 is marginally better at blasting its way through brick, concrete, and masonry than the older M855. The propellant in the M855A1 burns faster and thus produces a smaller muzzle flash when fired from the short (compared to the M-16) barreled M-4 rifle. The greater penetrating power of the M855A1 is because of a steel penetrator, which also makes the M855A1 more likely to penetrate body armor and sheet metal. The Taliban are increasingly getting their hands on protective vests or adding armor to vehicles (particularly suicide car bombs meant to speed past armed guards).
While this non-lead policy burnishes the army's image and environmental cred, it was also feared that it might equip troops with an inferior bullet, which was built around a copper alloy (not lead) slug. But inferior to what? Well to a another new bullet. SOCOM (Special Operations Command) had developed a new 5.56mm bullet, the Mk 308 SOST (Special Operations Science and Technology) round. The SOST bullet solves a problem the M855 has long had, the inability to penetrate things like automobile windshields. SOST uses lead and also has more killing power than the M855 (that did not inflict as much internal damage, and bleeding, as 7.62mm and 9mm rounds). The M855A1 turned out to perform these tasks as well, or nearly as well, as SOST and was still "green" (less polluting).
The army spent over $32 million developing the M855A1. The new bullet is more expensive (because of the more complex manufacturing process) and in the field troops have not noticed much difference. On the down side, the new round generates more pressure in the chamber (and higher speed leaving the barrel). In theory this causes a slight increase in the risk of a rifle exploding. That has not happened yet.
Some green bullets have been disasters. Norway introduced one three years ago that made users sick. It seems the new bullet, when used in new rifles, created some toxic gasses. A redesign of the new round fixed the problem and made the new bullet even more expensive.
The water is still safe to drink.