One key action will require more gun sellers to be federally licensed and perform a background check for every attempted purchase. Tens of thousands of dealers already follow these rules, but many others are able to evade them by relying on vague language in the law. While they are a small fraction of all unlicensed sellers, these dealers account for an outsized percentage of guns sold, according to a study by the advocacy group Everytown for Gun Safety. For obvious reasons, they are also more likely to appeal to criminals and others trying to hide from the authorities.

The law will be clarified to consider not only how many guns these dealers sell, but also how quickly they resell them after purchasing them, whether they sell them in their original packaging and how much they profit.

The president is also taking steps to improve the functioning of the federal background-check database, a critically important tool that has stopped millions of sales of weapons to prohibited people since 1998. Among other things, the F.B.I. will work to notify state and local authorities whenever a prohibited person tries to buy a gun and is rejected. This is a sensible and proven approach to reducing gun crime. In Virginia, follow-up investigations of those denied a gun because of a background check have led to more than 14,000 arrests.

Other presidential actions include delivering a budget proposal with money for 200 new agents and investigators for the Bureau of Alcohol, Tobacco, Firearms and Explosives to help enforce existing gun laws; requiring dealers to notify authorities when guns are lost or stolen in transit; increasing law enforcement access to mental-health records; and providing funding for research into gun-safety technology.

None of the actions will make a big dent in America’s gun-violence epidemic, but that’s because Mr. Obama can do only so much on his own. Congress could pass far more expansive and effective legislation, such as universal background checks, which have been associated with large declines in gun deaths in the 18 states that have implemented them.