Gun control: in Congress . . .

Progress against handgun violence - already too labored and limited - must be continued, not slowed. Provisions of the McClure-Volkmer bill, which would put gun sales to nonlicensed buyers back into the mails for the first time in 15 years, should be defeated.

On Nov. 19, 1963, just three days before President John F. Kennedy's assassination, these columns urged Congress to bar the mail-order sale of handguns.

''If passed and enforced,'' we wrote of a pending Senate bill, ''it would keep mail-order guns out of the hands of trigger-happy juveniles, criminals, mental defectives, and others who use the anonymity of this type of purchase as a means of obtaining firearms.''

Two decades later, the toll from gun-related violence is still with us: averaging 22,000 deaths a year, from some 8,000 homicides, 13,000 suicides, and 1,000 or more accidents. Close to 2 million new handguns are still produced in the United States each year.

In the decade and a half since passage of the Gun Control Act - in 1968, after the shootings of Robert F. Kennedy and Dr. Martin Luther King Jr. - the number of handguns owned by Americans has increased at least 30 percent, from 25 million in the late 1960s to 35 million today. Since the bill passed, 350,000 Americans have been slain by handguns.

Today, Congress is again considering handgun controls - but more in the direction of softening legal constraints on dealers and mail-order buyers of the weapons than in restricting handgun flow. Congress also is weighing the status of armor-piercing bullets, which even law enforcement officers see no reason to manufacture.

The Supreme Court last week sent back to a state court (Illinois) the issue of an individual town's right to ban handguns, refusing to reconsider lower federal court approval of the town of Morton Grove's initiative. And a new phase of handgun control has turned up in the form of product liability lawsuits, whereby manufacturers and dealers are being sued for acts of violence involving concealable handguns.

What can be said now of so tragically persistent and politically contentious an issue?

First, the volume of firearms still held by private citizens has by no means been reduced. The 1968 legislation did not really curb legitimate buyer access to guns, as gun owners feared. Neither did it save the public from the tragic carnage of gun violence, as control advocates hoped. The act failed to deal forthrightly with the cheap handguns used mostly in crimes, imposing instead import restrictions that led to a larger domestic handgun industry.

What the act did was allow authorities a better chance to monitor the flow of arms, not control or stem it outright.

The gun measure nearest a vote now, the McClure-Volkmer bill, would (1) pay gun dealers' attorney fees in so-called bad-faith prosecutions brought by the Treasury Department; (2) exempt dealers from spot-checks of their records; (3) exempt convicted gun dealers from the general ban on the ownership, purchase, or sale of handguns by felons; (4) permit people who are under indictment for any type of crime, even murder, to own guns; and (5) permit mail-order purchase of handguns between individuals, as long as the transacting parties claim they had at some earlier time met.

Issues of special legal treatment for gun dealers, verification of whether parties had actually met, and adequate record-keeping of transactions (often crucial in criminal prosecution) are raised by this bill. The Reagan administration is also concerned enough over the mail-order records aspect that it wants at least one dealer involved in any interstate gun sale (today, only licensed dealers can exchange weapons by mail).

The Reagan Administration Task Force on Violent Crime recommended reforms for the 1968 Gun Control Act: forbidding import of snub-nosed handgun parts, requiring owners to report the theft or loss of guns, mandatory jail for gun use in a federal felony, and requiring a waiting period and criminal records check for handgun buyers. These should be enacted.