WESLEY CHAPEL — When Arthur C. Hayhoe retired from an insurance career in 2003, his plan was to play golf.

Instead of a hobby, he found a cause: tightening Florida's gun laws.

"Everybody who retires ought to have something they care about," Mr. Hayhoe told the Tampa Bay Times in 2002. "My golf clubs are still in the corner. I've kind of put my retirement on hold indefinitely."

Mr. Hayhoe, who served as the volunteer executive director of the Florida Coalition to Stop Gun Violence and Floridians for Gun Safety, died Monday, Sept. 8. He was 82. Relatives said his health began to decline after he underwent shoulder surgery several months ago.

From his double-wide mobile home, the lifelong bachelor was a statewide one-man band in his efforts to support cities seeking to ban guns from the workplace and to work with opponents of shooting ranges. He appeared at debates around the area and unsuccessfully fought to get the Pasco County Commission to enact waiting periods and background checks for firearms bought at gun shows.

When the Florida Legislature approved the "stand your ground" law that allows the use of deadly force anywhere a person can lawfully be in 2005, Mr. Hayhoe passed out fliers at the Miami airport warning visitors not to antagonize the locals.

"That was his baby," said his niece, Christine Phillips. "He was always talking about it."

Mr. Hayhoe did more than talk. His name came up more than 50 times in the Tampa Bay Times archives since 1988, mostly in letters to the editor and in stories about gun laws.

"Unfortunately the Second Amendment was hijacked by the insurrectionists and turned into a bulletproof right-to-own any and all guns without any legislative constraints, something our founding fathers never intended," Mr. Hayhoe wrote in a letter published March 28, 2013, after Pasco County commissioners opted not to close the gun show loophole.

Even Bill Bunting, a Pasco GOP and gun rights activist, admired the resolve of his nemesis.

"I've never seen anybody more passionate than him," said Bunting, who squared off with Mr. Hayhoe, a Democrat, in numerous debates over the past 20 years. "He worked hard. I've got to give him credit."

Mr. Hayhoe earned an associate's degree in electronics from the Milwaukee School of Engineering. He spent a decade in Vietnam, first with the American Red Cross, then with American contractors supporting military operations. He worked as an engineer in Saudi Arabia from 1975 to 1985, then went into insurance sales.

From 1990 to 2003 he was a marketing director for WellCare Health Plans of Florida.

"He was the most intelligent man I've ever known," said his nephew, David Hayhoe. "He's been all over the world."

He said his uncle kept his online subscription to the New York Times right up to the end.

Mr. Hayhoe once was a member of the National Rifle Association, but his activism prompted the group to send him a letter in 2001 basically kicking him out.

Mr. Hayhoe framed it.