In the days after Omar Mateen used a Sig Sauer rifle to kill 49 people in Orlando and wound 53 others — the worst mass shooting in American history — the push to ban assault weapons as a way to stop rampages has gained new momentum across the country, from cable news networks to social media to petition-signing sites.

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Even horror author Anne Rice weighed in on Facebook, writing: “The one thing we do know for certain about these weapons is that they have figured in one horrific criminal massacre of innocent civilians after another.”

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Well, not exactly. Lost in the diatribes about banning assault weapons is this inconvenient fact: the vast majority of mass shooters use handguns, not assault rifles, in their attacks. That includes Seung-Hui Cho, who used two handguns, including a Glock 19, in 2007 to kill 32 people at Virginia Tech University, the previous worst mass shooting in American history.

A study last year by the Congressional Research Service found that from 1999 to 2013 assault rifles were used in 27 percent public mass shootings, which it defines as the killing of four or more people in a relatively public place. Dating back to 1982, the rate is 24 percent, according to research by James Alan Fox, a Northeastern University professor who studies mass murder.

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“Assault weapons are not as commonplace in mass shootings as some gun-control advocates believe,” Fox wrote in a 2012 article in the journal Homicide Studies.

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Why do they believe that?

Assault rifles, especially the AR-15, have been used in many high-profile attacks in the United States. Adam Lanza used a Bushmaster AR-15 at Sandy Hook Elementary School, killing 20 first-graders and six adults. The attackers in San Bernadino, Calif., late last year used assault rifles. And now Mateen.

The images of these weapons — identical in physical appearance to what Americans see U.S. troops using in war zones — have become a powerful symbol for an argument that Rice raises this way in her Facebook post: “What are the uses and purposes of military style assault weapons in private hands?”

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Legislators addressed that idea in 1994, passing an assault weapons ban in response to a series of mass shootings. The ban expired 10 years later and now there are calls to bring it, or something like it, back. Nearly 60 percent of Americans support a nationwide ban on assault weapons, according to a recent CBS poll, up 13 percent since last year.

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“The idea of restricting unfettered access to assault weapons is only considered radical when it comes out of the mouth of a modern US president,” the Globe argued in an editorial accompanying the front-page AR-15 image. “To most Americans, and every other democracy on the planet, it is rightly considered common sense.”

But in terms of mass shootings, what would such a ban really accomplish? Not much, according to history.

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From 1976 to 1994, there were about 18 mass shootings per year, according to Fox’s data, which is drawn from federal statistics. Between 1995 and 2004, a period covering the ban, there were about 19 incidents per year. And from 2005 to 2011, after the ban expired, the average went up to nearly 21.

Fox makes an important point about what probably happened during the ban: Mass shooters can rather “easily” come up with “alternate means of mass casualty if that were necessary.”

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In other words, if they can’t get an AR-15, they get a Glock. And that’s the problem, experts say, of hoping that a ban on assault weapons will stop mass shootings. It’s not really about the gun.

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Sure, some stats show higher kill counts with assault weapons than with handguns, but as Cho proved, that’s not always the case. (As my Wonkblog colleague Christopher Ingraham points out, high-capacity magazines — for rifles or handguns — might make a better focus for gun control advocates, but the symbolic images of clips aren’t as striking as an AR-15.)