A horrific school shooting was the last straw for the CEO of Dick's Sporting Goods

Edward Stack, the 64-year-old CEO of Dick's Sporting Goods, is an unlikely champion for gun control.

He's a hunter and gun owner who believes in the Second Amendment. The company, which his father started as a fish-and-tackle shop in 1948, has sold guns since long before Stack started working there in 1977.

But the mass shooting at a high school in Parkland, Florida, on February 14 2018, which killed 17, shook Stack to the core.

When Stack learned that the teen charged with the shooting had bought a shotgun at a Dick's store, he decided to make changes. It didn't matter to him that the gun wasn't used in the attack.

"We had a pit in our stomach," he told CNN soon after the shooting. "We did everything by the book that we were supposed to do, from a legal standpoint, we followed everything we were supposed to do. And somehow this kid was still able to buy a gun from us."

Stack called his management team together and told them what he wanted to do: No longer sell semi-automatic, assault-style rifles. Stop selling any kind of weapon to those under 21 years of age. Stop selling high-capacity magazines that hold a large number of bullets for semi-automatic weapons. He said his chief financial officer questioned what the financial implication would be.

"I basically said, 'I don't care what the financial implication is,'" he recalled at a recent appearance at the WSJ CEO Council.

Stack had been a relatively low-profile executive, but that changed when he took a stand on gun violence. He appeared on CNN and ABC's "Good Morning America" to announce his decision two weeks after the Parkland shooting.

"You know everybody talks about thoughts and prayers going out to them. That's great. That doesn't really do anything," he said on CNN. "We felt we needed to take a stand and do this."

Stack expected a backlash. He was firm in his decision, despite the potential harm to sales. "As we sat and talked about it with our management team ... it was, to a person, that this is what we need to do, that we need to take a stand on this," he said.

Overall sales did decline in the third quarter, in large part because of a drop in the sale of hunting gear, which includes guns.

Dick's wasn't the only retailer to take action. The same day Dick's announced its policy, Walmart said it would no longer sell guns to customers under 21 years old. It had previously dropped all sales of assault-style rifles. Retailer Fred Meyer, owned by grocer Kroger, dropped sales of all weapons after first stopping sales to those under 21.

Stack met with the Parkland victims' families — privately, without any media coverage — to talk with them about what they had gone through, and why the company was taking the steps it did.

Fred Guttenberg, the father of Jaime Guttenberg, one of the girls killed at the school, said he had been shocked, and grateful, that a sporting goods retailer would make such moves. But he came to appreciate it more once he and other family members met with Stack.

"They made a decision [to limit gun sales] because they believed they were doing the right thing," Guttenberg told CNN Business. "They weren't trying to get anything out of it. Meeting with us was not at all for PR."

Dick's announced it would destroy its inventory of weapons, rather than allow them to be sold by another retailer. And it hired three Washington lobbyistts to push for gun control.

Those steps caused it more problems. Several gun manufacturers announced they would no long sell guns through Dick's.

Iver Mossberg, CEO of gunmaker O.F. Mossberg & Sons, pulled the company's products from Dick's and urged people to stop shopping at Dick's. "Consumers are urged to visit one of the thousands of pro-Second Amendment firearm retailers to make their purchases," Mossberg said.

It wasn't all criticism, however. Gun-control advocates cheered Stack's decision. Some stopped by stores to bring flowers and donuts. And even with the drop in sales, the company is doing well. Profits were up in the third quarter even as sales were down.

While the chain was started by, and named for, his father, Ed Stack is the one who made it what it is today — the nation's largest sporting goods retailer.

When he took over in 1984, the chain had two stores. Today it has 861. It's adding stores while other retailers close theirs.

Correction: Ed Stack is a gun owner, but does not hunt. A previous version of this story misidentified Stack as a hunter.