IT WAS JUST one way for a financially strapped police department to save a few dollars, but trading seized guns to private dealers is bad business. Fairfax County police, who have done this routinely for years, should not be fueling the raging firearms supply in this country. It is not that this practice amounts to a police partnership with criminals; so far, checks show one handgun that went from police to a dealer and eventually to a juvenile charged in connection with a drug crime in Richmond. Whatever the percentage of guns traced to crimes, police recycling of guns back onto the streets is not sensible public policy, as national law enforcement agencies have noted.

Every major jurisdiction in the region, including state police in Maryland and Virginia, melts down seized weapons that are no longer needed as evidence. A federal gun buyback program in public housing projects, announced Thursday by President Clinton, also stipulates that the weapons be destroyed.

Although the Fairfax department hasn't traded any weapons to dealers this year, the arms traded in to licensed dealers over the past four years amount to a considerable arsenal: 655 semiautomatic handguns, revolvers, rifles and shotguns. J. Thomas Manger, who took over as police chief in January, says he supports ending the practice. So does Kate Hanley, chairman of the Fairfax board of supervisors, who wants assurances that the practice has been stopped for good. The board ought to make that official policy.

Police officers, whose lives are constantly threatened by armed criminals and disturbed people, have all the more reason to be troubled by the practice. Last year, the International Association of Chiefs of Police urged police agencies to destroy guns that are turned in or seized. Larry Todd, chief of police in Gatos, Calif., who helped draft the resolution, makes the point: "It did not make sense for us to be introducing guns back into the communities we were sworn to protect."