THE CRACKDOWN by the Treasury Department on the illegal sale of handguns in central and south Virginia is long overdue. Despite the murderous effect its policy is having on its neighbors, Virginia continues to ignore the threat posed by its casual treatment of the handgun problem. Indeed, to listen to some of the state's politicians talk, you might think they take pride in Virginia's growing reputation as handgun supplier to the East Coast. Given that attitude, the best hope of cities, like Washington, that are trying to control handguns is steady pressure by the federal government on gun dealers throughout Virginia.

The Treasury Department's Bureau of Alcohol, Tobacco and Firearms says that its agents had little or no trouble buying guns in 23 of the 78 Virginia gun shops they checked, even though the agents posed as out-of-state residents, to whom sales are illegal. The stores either ignored the law or arranged for fake purchases by Virginia residents in an effort to evade it. Transactions of that kind have been going on for a long time. Of 7,900 handguns confiscated after they were used in the commission of crimes in the District of Columbia, 27 per cent of those that could be traced came from Virginia gun shops. That's because guns are so easy to get in the Old Dominion and so profitable to bring into the District. You can make about 75 per cent by buying a gun in rural Virginia and selling it on the streets of Washington.

At the same time the Treasury agents were working to shut off some of the flow of guns into Washington and other East Coast cities, the Republican candidate for governor, John N. Dalton, was exploiting his opposition to gun control as a campaign issue. He has attacked Henry Howell for having supported what was at best minimal gun-control legislation - a law to bar the sale of guns to minors, felons, habitual drunkards, drug addicts and the insane. Mr. Dalton's view on this subject (like that, we regret to say, of the vast majority of Virginia politicians) is that no form of gun control is acceptable. This view not only ignores the problem Virginia is creating for its neighbors: it also reflects a lack of understanding of the crime problem in urban areas. As long as this view is the prevalent one among officeholders and would-be officeholders in Virginia, the ability of the District of Columbia to win its war against handguns will depend heavily on raids like the one the Treasury conducted this week.