Walmart Inc. is stopping ammunition sales for assault-style rifles and handguns, further restricting the retailer’s gun-related sales and policies after two deadly shootings at its stores last month.

Recent mass shootings have raised pressure on retailers and policy makers to take steps to reduce gun violence. Walmart’s ammunition changes exceed the measures taken by other big retailers that have tightened their gun policies in recent years after other deadly shootings.

Lawmakers are set to return to Capitol Hill after a summer recess as expectations for possible gun legislation run high. White House officials have met with congressional aides to discuss potential measures to tighten background checks and boost mental-health services. The man who went on a deadly shooting spree across West Texas on Saturday was barred under federal law from owning or buying firearms because a court had previously determined he was mentally unfit, according to law-enforcement officials.

However, doubts remain that Congress will get anything done on the issue with the 2020 election looming and because President Trump hasn’t endorsed a specific legislative package. Senate Majority Leader Mitch McConnell (R., Ky.) said Tuesday that he would follow the Republican president’s lead on gun policy rather than having the Senate chart its own course.

Walmart, the nation’s largest retailer, said Tuesday that it would no longer sell short-barrel rifle ammunition—used in assault-style guns and some hunting rifles—as well as all handgun ammunition in its stores.