The AR-15 is more than a weapon.

It is a potent symbol with a grip on the American imagination — a readily available and easy-to-use killing machine wielded during some of the country’s darkest moments, and a tactical weapon championed as the ultimate expression of Second Amendment rights. It is also a lucrative consumer product with a distinct appeal: The more controversial it becomes, the better it sells.

To understand the AR-15 and its impact, The Washington Post interviewed more than 200 people with expertise or relevant firsthand experience — including firearms Industry executives and lobbyists, gun owners, shooting survivors and victims’ families, lawmakers, trauma surgeons, first responders, activists, armed militants, academics and ballistics experts, among others. Our seven-month examination also relied on a review of more than 1,000 pages of documents, including internal company records, court and regulatory filings, and autopsy reports, many of them obtained through public records requests. And, in the most detailed poll of its kind to date, The Post partnered with Ipsos to survey hundreds of AR-15 owners about their reasons for having the weapon.

Here’s what we learned:

A flip by the gun industry: The AR-15’s rise over the past two decades was sparked by a dramatic reversal in strategy by the country’s biggest gun companies to invest in a product that many in the industry had long viewed as anathema to their culture and traditions. The industry embraced the gun’s political and cultural significance as a marketing advantage as it looked for new revenue. Manufacturers rode a post-9/11 surge in military admiration while also stoking a desire among new gun owners to personalize their weapons with tactical accessories. Gun companies seeking to rebrand the AR-15 have used images of police and soldiers wielding tactical rifles in the field, urging civilian buyers to, as one ad put it, “use what they use.”

Spikes in consumer demand: While handguns account for the most gun-related killings in the United States, sales of AR-15s surge in times of tragedy and political change. They soared in the run-up to the election of Barack Obama in 2008, and after the mass killing at Sandy Hook Elementary School in 2012 and a high school in Parkland, Fla., in 2018, and again ahead of the turbulent 2020 presidential election. AR-15s, which once accounted for a small fraction of guns produced in the United States, now represent nearly 1 in 4, according to industry and government figures.

Who owns AR-15s and why: About 1 in 20 U.S. adults — or about 16 million people — own at least one AR-15, according to new polling data from The Post and Ipsos. Self-defense is the most popular reason for owning one, with many respondents also citing recreation, target shooting and hunting. Compared with Americans as a whole, AR-15 owners are more likely to be White, male and between the ages of 40 and 65. They’re also more likely than adults overall to be Republican and to live in states Donald Trump won in 2020. The industry, meanwhile, has shifted operations in many cases to more culturally welcoming terrain. Numerous firearms, ammunition and gun accessory companies have moved headquarters or production facilities from liberal to conservative states, where communities see the companies as sources of jobs, not controversy.

The gun’s brutal efficiency: The AR-15’s mechanics, which allow shooters to easily fire bullets at a high velocity in rapid succession, make the weapon lethal and destructive. When the bullets penetrate the body, they create a blast effect that blows up organs and pulverizes bones. The weapon’s power magnifies the impact of Gun Violence, both because of the number of victims and, for survivors, the long-lasting effects on physical and mental health. In Sutherland Springs, Tex., where more than two dozen people were killed during an eight-minute rampage in 2017, the additional 20 people injured continue to grapple with debilitating, lifelong conditions such as paralysis or infertility. More than 90 percent of gun-related homicides involve handguns, according to the FBI, but 10 of the 17 deadliest U.S. mass killings since 2012 have involved AR-15s.

Escalating arsenals: In response to years of right-wing violence and intimidation linked to the AR-15, some far-left activists have begun to form armed groups, billed as community defense, often turning to the AR-15 as their weapon, as well. Some leftist activists who long favored nonviolence have grown more tolerant of armed support at public events as threats against the LGBTQ community and other vulnerable groups rise and faith in Law Enforcement recedes.

Outgunned police: Police departments that once deferred to SWAT teams wielding military-style rifles for active-shooter situations have started equipping officers with AR-15s and other long guns, as those weapons have flooded the neighborhoods they patrol. Many officers welcome the change, some buying their own AR-15s and using them for sport. But police often say they still feel outgunned and ill-prepared — hampered by a lack of training and by public demands that they do everything possible to avoid using force.

A path to fewer deaths: Many gun violence experts and law enforcement veterans say that restricting the sizes of ammunition magazines would lessen the carnage caused by AR-15s and other guns. Smaller capacity magazines would force shooters to pause during their attacks to reload, allowing people to flee or fight back, research shows. Most states do not limit magazine sizes, but in the past year, four states have capped them at anywhere from 10 to 17 rounds. Such efforts face growing legal challenges, and the issue could ultimately wind up before the Supreme Court.