Gun owners are married or single. Some have children. Many have pets, usually cats.

They have clean, almost sparse homes, or messy ones with unmade beds. The men are just as likely to wear camouflage - three - as they are to put on skirts or kilts - four. A few chose suits, one donned a Renaissance Faire costume, one wore his chef's whites.

In short, gun owners can pretty much look like anyone.

It's inaccurate to say the gun issue is hot right now, as it always seems to be. The difference is only in the intensity, and the fires are burning now.

Last week, the U.S. Supreme Court declared that Americans have a constitutional right to have guns in their homes for self-defense, a decision that drew applause from the pro-gun people. Since taking office in January, Mayor Nutter has pushed gun-control laws that some say will fight crime in a city that averaged more than a murder a day in 2007. Others say they harm the law-abiding.

The passionate on either side might enjoy Cassidy's book if only to see if it reinforces their stereotypes.

Cassidy, 42, traveled 15,000 miles across the United States to shoot this collection. The West Philadelphia resident said he previously bought into the idea that a gun owner was "a guy in a dirty baseball cap with a pickup truck with a Bush/Cheney sticker on the back."

"Ultimately, so much of it surprised me," he said. "It made me realize we put so many stereotypes on people based on how they look or what their favorite movies are or what they wear. I realize I'm doing it all the time. We're all doing it all the time."

Since the book was released last summer, it has garnered international attention. For some, it reinforces the stereotype of the gun-happy American. An Australian newspaper noted that guns were a "U.S. obsession": "A home arsenal is all part of living the American dream."

Even a largely evenhanded article in a London paper ended with: "Meanwhile, the security moms are still buying more handguns, waiting for an attack on middle America by snipers from Al-Qaeda."

But in the United States, discussion has been more fair.

"It's part of the fabric of America, this debate," Cassidy said. "This book can be used by people on both sides. I'm pleased if that happens."

To meet gun owners, Cassidy had to become one. When he first went to a South Philadelphia shooting range and proposed his project, the reaction was not positive. "I think a lot of people suspect you're going to judge them, especially in Philadelphia, where there's so much gun violence," he said.

So he began target shooting, eventually buying a handgun. He found he liked it - and the people he met.

After six months, he had his first subjects, and from there it was a domino effect, with one subject contacting a friend or posting a picture on a blog.

Cassidy kept himself neutral: Most of the text in the book is the subjects' answers to the question "Why do you own a gun?" The answers, he found, created four general categories - hunters, sportsmen who enjoy forms of target shooting, self-defenders, and constitutionalists. They range from "I just think it's a good thing to have" to "As the founding fathers said, sometimes the tree of liberty must be watered with the blood of tyrants and patriots. If that day comes, I will be ready. . . ."

The subjects chose their clothes and generally the background for the photo. When one subject offered a meticulously arranged gun display, Cassidy agreed that was the best place to shoot, indicating that the way the man had laid out the weapons "said more than I could ever say about him."

Sometimes, Cassidy chose the location for the photo, looking for interesting elements like an old church organ in one house or a room filled with hunting trophies.

Since the book hit the streets, none of the more than 100 people photographed has complained about a photo, Cassidy said. Many, like West Philadelphia residents Donno Layton and Judi Gilbert, are thrilled.