In New York City, where taking illegal handguns off the streets is high on the mayor’s agenda, thousands of firearms make it into the hands of law enforcement officers each year.

Once they’ve been seized in crimes, whether after long and ignominious careers or short but violent ones, and once their owners have been prosecuted, the guns must be destroyed, never to be used again.

The New York field office of the federal Bureau of Alcohol, Tobacco, Firearms and Explosives periodically takes the guns it gathers to an industrial stretch of road in Westchester County, about 20 miles north of Manhattan, to a scrap metal processing plant in Elmsford, N.Y. There they are chopped up into tiny pieces and sold for about 25 cents a pound.

In the words of federal agents, it is where guns go to die.

Their steel remains are shipped to foundries as near as New Jersey or as far as China, India or Turkey, said Daniel J. Graap, 39, the co-owner of the plant, Brookfield Metal Company. The steel is ultimately used to build, say, iron water pipes, reinforcement bars, chain-link fences or appliances.