No Matter the ‘Details on These Shootings,’ Biden Says, Congress Should Respond by Banning ‘Assault Weapons’

Los Angeles County Sheriff Robert Luna says the gunman who killed 11 people at a dance hall in Monterey Park, California, on Saturday used a “9mm caliber semiautomatic MAC-10 assault weapon.” Citing “a law enforcement official,” CNN reports that the gun was “a Cobray M11 9mm semi-automatic weapon,” which is modeled after the MAC-10 but unlike the military version fires just one round per trigger pull.

Police say the gunman who killed seven people at two farms in Half Moon Bay, California, two days after the Monterey Park massacre used a legally purchased semi-automatic handgun. So far they have not specified the make and model.

Do these details matter? Yes but also no, judging from President Joe Biden’s response to the two mass murders.

“Yesterday, Senator Feinstein—alongside Senators Murphy, Blumenthal and others— reintroduced a federal Assault Weapons Ban and legislation that would raise the minimum purchase age for assault weapons to 21,” Biden said on Tuesday. “Even as we await further details on these shootings, we know the scourge of gun violence across America requires stronger action.”

Regardless of what “further details” might reveal, in other words, Biden thinks banning “assault weapons,” or at least restricting their sale to people 21 or older, is a rational response to these crimes. As he sees it, “stronger action” is obviously necessary, even if that action is not logically related to the incidents that prompted his statement.

In the context of the two California shootings, the age restriction Biden mentioned is clearly a non sequitur. The Monterey Park murderer, who killed himself before he could be arrested, was 72. The Half Moon Bay suspect is 66.

It’s true those attackers were unusually old. “The median age of mass shooters in the United States”—defined as assailants who kill four or more people—”is 32,” criminologists Jillian Peterson and James Densley report. Prior to the recent California attacks, they note, the median age was declining: “From 1980 to 1989, the median age of mass shooters was 39. Over the next two decades, it was 33. And from 2010 to 2019, it was 29. Since 2020, the median age of mass shooters has come down to just 22.”

Last June, The New York Times reported that “only two of the 30 deadliest mass shootings recorded from 1949 to 2017 involved gunmen younger than 21.” But in the nine deadliest mass shootings since 2018, the Times noted, four of the perpetrators were younger than 21.

Those trends help explain why Biden and his allies in Congress are focusing on 18-to-20-year-old gun buyers, notwithstanding the ages of the California gunmen. But perpetrators younger than 21 still account for a relatively small share of all mass murderers, who typically are in their 20s or 30s. More to the point, restricting access to “assault weapons,” whether through an age limit or a general ban, can reasonably be expected to have a meaningful impact on mass shootings only if those firearms are uniquely suitable for killing large numbers of people.

Biden himself has conceded that they are not. In a 2019 New York Times essay, he complained that manufacturers “circumvent[ed]” the 1994 federal “assault weapon” ban, which expired in 2004, by “making minor modifications to their products—modifications that leave them just as dea