Give the new Bush administration credit for moving quickly to correct a bad blunder.

Even after a drifter massacred children in a Stockton, Calif., school-yard in January with an AK-47 assault rifle, President Bush said he was reluctant to crack down on semi-automatic weapons though they can spew out dozens of rounds of ammunition a minute and though most Americans were surprised to learn that such firearms can easily be purchased over the counter.But now the administration has executed a sensible about-face. Acting only one day after being sworn in as coordinator of the federal government's anti-drug effort, William Bennett announced this week an immediate suspension on the import of AK-47s and similar weapons.

This policy change reflects official recognition of the extent to which such assault rifles, which can easily be converted from semi-automatic to fully automatic, are increasingly used by criminals, particularly drug dealers.

The change also reflects the alarming increase in the number of these weapons being brought into the United States. As recently as 1986, only 4,000 assault-type rifles were imported. The figure soared to 40,000 in 1987, and 44,000 last year. Now applications are pending to import nearly 114,000 of the rapid-fire guns.

The new suspension is no cure-all. It applies only to imports, not to the manufacture and sale of similar weapons made in the United States; three times as many are made by American firms. However, Colt did suspend manufacture of its AR15 assault rifle this week.

The purpose of the government suspension is simply to provide time for a study on whether assault rifles are really suitable for hunting, as some claim.

But it's hard to believe the study can come to any conclusion but one. As this page noted in January, police agencies already have concluded that assault rifles are too powerful to be used in hunting or target practice. Otherwise, why would assault rifles have become increasingly used in street crimes and as a favorite weapon of violent youth gangs?

Moreover, the new review offers hope of changing the present, indefensible situation that makes it possible to legally buy semi-automatic weapons without even going through the waiting period required to purchase a handgun while law officers check the buyer's police and medical records.

By no means does this situation justify declaring open season on all types of guns. But the new look being taken at assault rifles is clearly in order.