Glock Could Make It Harder to Outfit Its Pistols With Switches — For a Price

In early July, multiple shooters fired more than 100 bullets into a crowded block party on the east side of Detroit, wounding 19 people and killing two. The police recovered nine weapons at the scene, including a Glock fitted with a “switch” — a thumbnail-sized device that enabled the pistol to fire as many as 20 rounds per second.

Switches, also known as auto sears, were specifically designed to slot into the back of Glock handguns, effectively turning them into machine guns. They are neither sanctioned nor manufactured by Glock, and are typically 3D-printed or purchased over the internet from overseas. 

Most of the switches in the United States are illegal. Over the past decade, Glocks outfitted with switches have increasingly turned up at crime scenes. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) reported last year that it had recovered more than 5,400 switches and other conversion devices between 2017 and 2021 — a 570 percent increase from the preceding five years.

Glock is one of America’s most popular brands of handguns, but the proliferation of switches has put pressure on the company to overhaul its products. The city of Chicago is pursuing a lawsuit demanding that Glock alter its handguns to resist switches, accusing the gunmaker of jeopardizing public safety. Thirteen state attorneys general have signaled their intention to file similar suits. In New York, a state senator has proposed legislation to ban the sale of Glocks until the company changes its designs. 

While Glock did not respond to requests for comment for this article, the company has previously said it has no responsibility to prevent criminals from misusing its products and that it cannot change its pistols to make them more difficult to modify. But The Trace spoke with legislators, former Glock employees, and firearms experts — including the inventor of the switch — and all said the gunmaker has several possible, if costly, solutions. 

Jorge Leon, who invented the switch but has since disavowed it because of its frequent use in shootings, said Glock needs to change its designs to address the proliferation of machine gun violence in a meaningful way. “Glock created this problem,” he said. “The switch is a consequence.”

The ATF is charged with regulating the manufacture and sale of machine guns. As The Trace has reported, the agency has ruled that semiautomatic firearms that are “readily convertible” to fully automatic fire are machine guns under the law, and thus subject to registration requirements and a special tax. The ATF has not enforced this ruling against Glock.

In other industries, regulatory bodies like the Federal Aviation Administration or the National Highway Traffic Safety Administration can prescribe standards to limit the way products are built. But no such agency exists in the firearm industry. The Consumer Product Safety Commission, which oversees the sale of virtually every other consumer good, has no authority to recall firearms or to investigate injuries caused by allegedly defective guns. 

New York State Senator Zellnor Myrie, who introduced the bill that would ban the sale of Glocks in the state, said it’s important for state legislatures to “use every tool at their disposal to introduce some regulatory framework.”

“This is a problem we believe can be fixed with the appropriate manufacturing approach,” Myrie said. “Frankly, it’s a problem Glock has been aware of for decades, and they have seemingly put their profits over the people.”

Glock pistols are striker-fired, one of the most popular types of handguns. They work sort of like a bow and arrow: Each pull of the trigger draws back a spring-loaded metal pin called a striker and then releases it. The striker springs forward to hit the round, causing a small explosion that propels the bullet out of the gun. 

That explosion also causes the gun’s upper half — its “slide,” which houses the striker — to recoil backward, effectively re-cocking the gun. Because the slide is also held in place by a spring, it is wrenched forward with enough momentum for the striker to fire another bullet. 

A small metal foot called a sear is designed to catch the striker before it hits another round, but a switch overrides this mechanism, depressing the sear as the slide rushes forward after each recoil. With the sear depressed, the striker is able to slam into the next round, causing the cycle to repeat. The gun will continue firing until the trigger is released, which is why switches are also known as auto sears.

Leon, the switch’s inventor, said one reason the device works is because of Glock’s unusual sear. In most striker-fired guns, the trigger is connected to the sear by several different components working in unison like the gears in a machine. But in a Glock, the sear is connected directly to the trigger — it’s all one part. This means that as long as the trigger is being squeezed, the sear will remain in reach of the switch, enabling continuous fire. 

Glocks, like many striker-fired guns, also have a removable backplate to allow easy access to the weapon’s internals for cleaning and assembly. Leon specifically designed the switch to replace this backplate, ensuring the device fits into the opening once the plate is removed. 

With its newest generation of pistols, known as the Gen5, Glock added a polymer block on the back of the gun, presumably to prevent a switch from being installed. But many Gen5 owners who want to use a switch simply sand the block down with a metal file.

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Firearm experts said there are many other possible fixes. 

“The easiest, fastest, cheapest way would be to make a slide cover plate that cannot be removed,” said James Elwood, a former Glock armorer who worked in the company’s testing and evaluation department for six years. With a permanent backplate, a switch couldn’t be inserted. 

But Elwood said this kind of a change would make the gun much more difficult for owners to clean and inspect — undercutting some of the gun’s chief selling points.

Other solutions would require Glock to redesign or rearrange the gun’s internals so that no intrusion from a switch could disable the sear without more serious gunsmithing. In its lawsuit against Glock, Chicago alleges that the engineering effort required to convert other popular pistols into machine guns is “well beyond the capability of most civilians.”

A former Glock factory worker, who asked to remain anonymous because they were not authorized by the company to speak publicly about its manufacturing processes, said changing the gun’s internals would require Glock to retool and alter its assembly line — an extremely costly step. “Changing that production line would mean a ton of money for any manufacturer,” they said. “That’s the bottom line.”