US President Donald Trump has signed an order to ban bump-stock devices, which were used by a gunman who killed 58 Las Vegas concert-goers last year.
Speaking at the White House, Mr Trump said he had directed the Department of Justice to propose a law to make the accessories illegal.
The Republican president said that school safety was a "top priority" for his administration.
The gun control debate has been renewed by last week's Florida school shooting.
Students and parents affected by that massacre, which left 17 dead, are planning a demonstration in the state capital of Tallahassee on Wednesday.
What are bump stocks?
The accessories can make semi-automatic rifles fire as rapidly as machine guns.
They can be bought for as little as $100 (£70) without the need for a criminal background check.
The device was used by a 64-year-old gambler who rained bullets on a crowd at an outdoor country music festival on the Las Vegas Strip in October last year.
More than 500 people were injured in that attack, considered America's worst ever mass-shooting by a lone gunman.
Audio analysis found the attacker, Stephen Paddock, was able to fire 90 bullets within 10 seconds from his room in the Mandalay Bay Resort and Casino.
Both Democrats and Republicans agreed in the nationwide wave of horror following the Las Vegas attack that the sale of bump stocks should be outlawed.