WASHINGTON — A partially nylon bullet has emerged as a leading contender to replace lead bullets as the U.S. military's standard, pushed by military planners' desire for a slug that will not have the toxic cleanup problems of lead.
The military has spent about $9 million thus far and is partway through a multiyear research effort to find a deadly bullet that does not pollute the soil of firing ranges or give off noxious fumes when fired repeatedly indoors.
The nylon bullet — actually a blend of nylon and tungsten metal — is one of two prototypes that have emerged from among seven bullets examined initially. The other is a mix of tungsten and tin.
``It looks very promising from our perspective,'' said Jeffrey Marqusee, the manager of the Pentagon's environmental security technology certification program. ``This is a prime candidate we are looking at.''
The military research effort comes amid pressure from communities near military bases to move away from using lead in training exercises.
The U.S. Environmental Protection Agency, for example, took an unprecedented step earlier this year and told the Massachusetts Military Reservation, a large training base on Cape Cod, that it had to switch from lead bullets to plastic. The base sits on top of the only water supply for 200,000 people, and the soil is very sandy, according to an official at EPA's Boston office. EPA said it took the step before testing the soil, putting the burden on the military to demonstrate that the shooting range is not polluting the water supply.
Emissions from weapons also have forced the Army to close many indoor firing ranges.
Each of the two bullets in the testing program survived preliminary tests that demonstrated that they can be shot from military weapons at the same speed as lead slugs, and do as much damage to their targets, said Wade Bunting, technical executive for development of small-caliber ammunition at the Army's Armament Research Development Engineering Center at Picatinny Arsenal in Dover, N.J.
So far, the ``green bullets'' are cheaper to make and will save the Army several cents a round, or between $5 million and $20 million a year, Bunting said. That does not includes savings from cleanups avoided, he said.
But that will not matter if the new nontoxic bullets do not ``meet the same performance specifications'' — kill, in laymen's terms — at least as well.
``The performance has to be equal or better,'' he said. ``Obviously, cost is a driver, but my main driver is I can't degrade the performance.''
Next, the bullets undergo comprehensive environmental tests to make sure they do not pollute.
The bullets will be broken up and put in soil to see if shrubs absorb the bullet materials, Bunting said.
Most data indicates tungsten is nontoxic, but researchers want to be sure. Plus, they want to see how tungsten reacts in the presence of nylon, tin and the copper on the ammo jackets, according to Bunting.
``Theoretically, it looks real good,'' he said. ``By the same token, we're not going to make the environment worse.''
The bullets also will undergo medical-related tests, including looking at what happens if people swallow them, he said. And the bullets must be able to be mass-produced easily, said Marqusee.
Bunting would not release the name of the injection molder making the nylon composite bullets, but said molding them is not very difficult. The molder is getting a patent and does not want to talk about the development, he said.
The Army chose tungsten as a replacement for lead because it is the cheapest heavy metal, except for lead, he said.
But, because tungsten is about 50 percent heavier, it has to be combined with lighter materials, such as nylon and tin, to give it the same overall density as the lead slugs so it can work in existing weapons, Bunting said.
The new bullet is part of a larger military effort to clean up its weapons, resulting in changes, for example, in bullet manufacturing practices to eliminate emissions of some ozone-damaging volatile organic compounds, Marqusee said.