The call came Friday night, as Americans were just beginning the struggle to make sense of one of the most horrific mass shootings in a long history of them.

The anonymous caller was angry, and he was looking for Philip Van Cleave, who heads the Virginia Citizens Defense League. He cursed Van Cleave for his pro-gun advocacy, challenged Van Cleave to sell his weapons, and called him a coward.

“You would have thought I had gone up there and done these horrible things,” said Van Cleave, who received the call in the midst of planning demonstrations at two Autozone stores to protest the firing of an employee who used his firearm to break up a robbery.

Those who support the Second Amendment say they feel just as horrified and numb as any other American after Friday’s massacre of kindergartners and other young children at a Connecticut school. But now, as the call for new gun-control laws increases, gun owners say they also feel under attack.

These are the people who see guns as an answer to the problem of violence, not the problem itself. They worry that their Second Amendment rights will be taken away. Challenged by those who see any gun as an instrument of destruction, they defend their belief that guns are beneficial. Harder still is to explain the allure of weapons like the .223-caliber Bushmaster, a military-style semiautomatic rifle that a some want banned.

Read the stories of the Newtown shooting victims

“I could ask you why should anyone want a Ferrari?” Van Cleave said Sunday. “[Bushmasters] are absolutely a blast to shoot with. They’re fast. They’re accurate.”

And there’s no denying that their fearsome, combat-ready appearance adds to their appeal, he said.

“Guns are fun, and some of them are much more cool than others. It’s just like we have television sets that look cool, and others are much more boxy,” Van Cleave said.

Investigators say Adam Lanza used a .223-caliber Bushmaster to kill 27 people, including 20 children, at Sandy Hook Elementary School in Connecticut.

But none can say why.

Lanza, 20, killed himself before police arrived. He was also carrying two 9mm semiautomatic handguns, including a Glock. The guns belonged to his mother, a gun collector who was slain in her home before the rampage began.

Before Connecticut became home to what, for now, is perhaps the most infamous mass murder in the country, the state was arguably the place where the mass production of repeating firearms was perfected. Samuel Colt set up shop in Hartford in the mid 1800s to produce a firearm whose revolving chambers would feed bullets at a then-unheard-of speed, and it was his company that later developed the forebear of Lanza’s deadly rifle.

The Bushmaster is a civilian version of the M-16 military rifle and its descendents. The flash suppressors, designed to hide the muzzle flash from the enemy, have no practical use at the average shooting range, but they look fierce. Although not as powerful as many popular hunting rifles, such as the .30-06 caliber, whose bullet and cartridge are both larger, the weapon is made for high performance, with a large magazine and rapid rate of fire.

So is the Glock, a rapid-fire handgun whose sleek, modernistic design arose from its inventor’s desire to protect Austrian soldiers from their own clumsiness.

Gaston Glock wanted to find a way to avoid accidental discharges when the handgun was dropped. It was designed for combat, with a large magazine, a light trigger and no external safety. Its molded black plastic frame flexes to absorb recoil.

When the Glock first appeared on the U.S. market, it was the pit bull of firearms. Gun-control advocates warned that the Glock would become terrorists’ weapon of choice — the “hijacker’s special,” as one newspaper put it — because its plastic body might slip past metal detectors.

But controversy also brought more attention than any marketing campaign ever could. Tupac Shakur rapped about the Glock by name (he would later be killed by one), and Hollywood glamorized the handgun in movies such as “Die Hard 2.”

“Weapons that were targeted and demonized by liberals and gun-control advocates took on this dark glamour,” said Paul M. Barrrett, author of “Glock: The Rise of America’s Gun.”

This time, the nation’s grief is unlikely to pass quickly, and it’s already stoked with anger at a culture that glamorizes firearms. Gun-rights advocates said they too feel disgust and sorrow at the violence that snuffed the lives of so many children. But to people whose lives have been saved or made more secure by the presence of a firearm, they also feel as if they are on the defensive.

“We’re all horrified by this thing,” said John R. Lott, an economist whose book, “More Guns, Less Crime,” suggests that gun-control laws have had the unintended consequence of making mass shootings more likely. Referring to specific places, such as schools, Lott said, “The frustration a lot of people feel is what strikes me as most obvious: All these attacks in the U.S., and all of these attacks in Europe, except one, keep occurring where guns are banned.”

Gun-rights advocates say that, as horrible as this crime was, there does not appear to be a gun law that would have altered the equation, short of a weapons ban. Although a lot of attention has been focused on the Bushmaster, they argue that a prettier version of a semiautomatic rifle, such as a hunting rifle with a wooden stock and without the military-style features such as a flash suppressor, would be just as deadly.

Lott has also been receiving angry phone calls. Appearing on CNN, he was interrupted by host Piers Morgan, who demanded: “How many kids have to die before you guys say we want less guns, not more?”

But Lott said he is not a defender of the Second Amendment. He is not even a gun enthusiast. He was forbidden to have a BB gun as a child, and he and his wife would not let their children have toy guns. But Lott said the data do not lie: Since 1950, in every public mass shooting in which three or more people have died, the setting has in almost every case been one where guns are banned, such as schools.

But many gun-rights advocates were reluctant to be drawn into any discussion of their views so soon after the killings.

“This is a time of grieving. We need to respect these families,” Del. L. Scott Lingamfelter (R-Prince William), who led the effort to repeal Virginia’s pioneering law limiting handgun sales to one per month. “That’s all I have to say.”