Interest in his products, and in similar stocks from other companies, suddenly surged after Sunday when Stephen Paddock, equipped with a small arsenal of weapons that included a dozen rifles outfitted with bump stocks, massacred dozens of people and injured hundreds in Las Vegas. The distinct, jagged sound of the rifles has haunted newscasts for days.

Before long, retailers like Walmart and Cabela’s pulled bump stocks from their websites. Some gun owners, fearing an imminent crackdown, flooded social media looking to buy them.

Lawmakers, including Republicans in Congress, have called for bump stocks to be banned. The National Rifle Association said in a statement on Thursday that it “believes that devices designed to allow semiautomatic rifles to function like fully-automatic rifles should be subject to additional regulations.”

Slide Fire — which boasts on its website that it “revolutionized recreational shooting” — soon ran out of stock and stopped taking orders.

Mr. Cottle did not respond to multiple requests for comment, but said in an interview with Ammoland last year that highly regulated firearms like machine guns require “a mountain of paperwork sure to give you life-threatening paper cuts.”

But bump stocks, he said, can help a semiautomatic firearm recreate the adrenaline-inducing power of an automatic weapon.

“Some people like drag racing, some people like skiing and some people, like me, love full auto,” he told Ammoland.

Fiercely protective of his creation, Mr. Cottle has repeatedly — and successfully — sued competitors for patent infringement. But before this week, the product remained largely obscure except in certain gun enthusiast circles.

“It was only ever a niche product to begin with — it was a tiny component of the industry that wasn’t really well known,” said Rommel Dionisio, managing director at Aegis Capital. “It was never a significant seller.”

The AR-15 rifle and similar weapons — Mr. Paddock at least three such firearms in his hotel room — were banned under federal law from 1994 until 2004, when Congress allowed the ban to expire. Outfitting the AR-15 soon became “one of the fastest-growing segments of the firearms market,” Mr. Dionisio said.

Photo

A Slide Fire bump stock for a semiautomatic rifle at a gun store in Salt Lake City, Utah.

Credit
George Frey/Getty Images

“It’s considered the Mr. Potato Head of firearms, because you can put a lot of different accessories on it — barrels, sound suppressors, scopes and more,” he said. “The accessories market exploded.”

Equipment, apparel and supplies constitute 12.8 percent of the $2.5 billion online gun and ammunition industry, with ammunition, handguns and long guns making up the rest, according to IBISWorld, a market research firm.

Slide Fire sells online and also through a retail network that, within 11 months of starting business, included 500 outlets, according to The Albany News.

Mr. Cottle joined the military at 19 and was in the Air Force for nine years, attaining the rank of staff sergeant. He was involved in the Bosnia and Kosovo conflicts, and medically retired from the military after developing meningitis and encephalitis, he told The Abilene Reporter-News in 2006.

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Back in Texas, while out shooting with a friend, Mr. Cottle was frustrated with his weapon’s firing speed, according to The Albany News. He crafted a prototype bump stock out of wood and metal in two hours.

Mr. Cottle saw an opportunity. He sent a production model to the Bureau of Alcohol, Tobacco, Firearms and Explosives and, in June 2010, received a letter in response saying that the company’s bump stock product “is a firearm part and is not regulated as a firearm under the Gun Control Act or the National Firearms Act.”