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.
“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.
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.”
The letter noted that the stock “has no automatically functioning mechanical parts or springs and performs no automatic mechanical function when installed.” It also mentioned that Mr. Cottle’s letter had described the bump stock as “intended to assist persons whose hands have limited mobility to ‘bump-fire’ an AR-15 type rifle.”
The A.T.F. declined to comment on Thursday. On Sept. 16, the agency decided that the AutoGlove — a gauntlet with a battery-powered, motorized trigger finger than can allow its wearer to fire 1,000 rounds per minute — could not be used or possessed by individuals. The company issued refunds to all of its customers soon after, according to a cached version of its website.
Slide Fire’s product “grants shooters the freedom of controlled rapid fire without compromising the safety of themselves or others around them,” according to the company’s website. Mr. Cottle has appeared on YouTube promoting his bump stocks, priced from $140 to $300.
But the internet also abounds with tutorials on how to gin up homemade versions of the accessory using belt loops and rubber bands. On YouTube, videos show AR-15 rifles equipped with 3D-printed bump stocks and “bump boards” made of wood.
Mr. Cottle is listed as an inventor on several slide-action stock patents and has doggedly defended his products against copycats.
“The technology sets our company apart,” Mr. Cottle said in a video on the company website. “There is no one that does what we do.”
In 2014, Slide Fire sued Bump Fire, a company selling $99 bump stocks. Slide Fire alleged infringement on eight of its patents, winning a court judgment last year that forced Bump Fire to stop producing and selling stocks that functionally mirror Slide Fire’s products.
In early 2014, Slide Fire began an advertising campaign that included billboards with an image of a rifle next to photos of an apple pie and a baseball glove above the phrase “Pure American.” The display represented “the perfect symbolism for the core beliefs we hold here at Slide Fire,” the company said in a blog post.
The advocacy group Moms Demand Action for Gun Sense in America asked that one of the billboard, next to a busy Chicago freeway, be taken down. But Lamar Advertising Co. said in a Facebook post that it would “support the First Amendment right of advertisers and believe that it is in the best interest of our company and the communities we serve to accept advertising copy openly.”
Back home, Slide Fire is seen as a hometown anchor of sorts. Mr. Cottle hired local residents, including a former teacher and a neighbor, and became a major employer in the area, according to The Albany News.
He told the publication that the company’s success was a miracle.
“This is beyond a Cinderella story,” he said.