In one of the strongest actions taken by an American company in the national gun debate, one of the nation’s largest sports retailers announced Wednesday that it will halt all sales of assault-style rifles in its stores.

The decision by Dick’s Sporting Goods comes after several companies - including Atlanta-based Delta Air Lines -severed ties with the National Rifle Association following the Feb. 14 school shooting in Parkland, Fla., that left 17 people dead.

Dick’s also said that it would no longer sell high-capacity magazines and that it would not sell any gun to anyone under 21 years of age, regardless of local laws.

As of Wednesday morning, the company said all AR-15s and other semiautomatic rifles would be removed from its stores and websites.

“When we saw what happened in Parkland, we were so disturbed and upset,” said Edward Stack, the 63-year-old CEO of Dick’s on Tuesday evening. “We love these kids and their rallying cry, ‘enough is enough.’ It got to us.”

Some metro Atlanta gun store owners said the sporting goods retailer’s policy change is nothing more than a publicity stunt, but experts who follow corporate behavior say most companies struggle to make these types of public changes.

“Most firms will look back to their own stated missions and values to help guide them when difficult questions arise,” said Karie Davis-Novemack, an assistant professor of Law and Ethics at Georgia Tech. “Firms now understand they have responsibilities more than just the profit-making motive.”

However, Eric Lewis of Clyde Armory Inc. in Athens, says the announcement by Dick’s is a publicity stunt and that the company probably wasn’t selling many assault rifles at its stores.

“It’s just great advertising for them,” said Lewis.

It is unclear how much in revenue the Pittsburgh-based company earns from the sale of firearms as that information is not included in its financial reports.

This is not the first time Dick’s has made changes in response to a school massacre. In 2012, after the shooting at Sandy Hook Elementary School that killed 26 people, Dick’s removed assault-style rifles from its main retail stores. But a few months later, the company began carrying the firearms at its outdoor and hunting retail chain, Field & Stream.

Stack said the retailer began scouring its purchase records shortly after the identity of the suspected Parkland shooter, Nikolas Cruz, became known. The company soon discovered it had legally sold a shotgun to Cruz in November, though it was not the gun or type of gun used in the school shooting.

“But it came to us that we could have been a part of this story,’’ he said. “We said, ‘We don’t want to be a part of this any longer,’” said Mr. Stack.

Delta Air Lines decision decision to end discounts for NRA members has touched a political nerve among some conservative leaders in Georgia.

Lt. Gov. Casey Cagle, who is running for governor, recently threatened to kill tax legislation that benefits the airline unless the company rescinded its decision, arguing the company’s action was an attack against conservatives.

“Discriminating against law-abiding gun owners will not solve the problem,” Cagle wrote in a tweet.

Gov. Nathan Deal said he would reluctantly support a measure that stripped a lucrative tax break for Delta Air Lines but also includes broader cuts to the state’s income tax rate.

The Republican was a vocal supporter of the $50 million tax break, which would have eliminated the state’s tax on jet fuels. But Senate Republicans voted Wednesday to strip it out of the measure after Lt. Gov. Casey Cagle said he would “kill” the incentive unless Delta restored ties with a gun rights group.

At a press conference Wednesday, Gov. Nathan Deal said he was frustrated by the “antics” of Republicans seeking higher office and said he would still seek to salvage a tax break for Delta. But he said he couldn’t veto a measure that also amounted to a sweeping tax cut for residents.

Dick’s is not the first retailer to stop selling the semiautomatic guns. In 2015, Walmart said that it would no longer sell high-powered rifles in its stores in the United States. But Walmart sidestepped any controversy involving gun politics, attributing its decision to lower customer demand for the military-style rifles.

Over all, firearm sales for retailers and gun manufacturers have slumped since Donald J. Trump was elected president, as fears of stricter gun regulation receded. Firearm sales data for the United States is not readily available, but background checks tumbled more than 8 percent last year, the largest fall since the FBI began keeping track in 1998.

The New York Times contributed to this story