A controversial ban on selling “convertible pistols” like Glocks advanced at the state Capitol on Tuesday.

The aim is to get deadly “Glock switches” – a cheap piece of plastic that can turn a handgun into a fully automatic weapon – off the streets.

But nearly 2,000 people have rallied against the proposal, arguing that it could criminalize nearly every gun owner in the state.

Glock switches are illegal but they are easy to find – or even make yourself with a 3-D printer.

“You can order it off internet,” said recently retired FBI Special Agent-In-Charge John DeVito. “Print it in your backyard.”

Last year, DeVito showed News 12 Connecticut’s “Turn To Tara” how a $25 toy-sized part can turn an ordinary pistol into a makeshift machine gun in seconds. Glock switches depress the mechanism that prevents a handgun from firing multiple rounds at once.

The device gets its name because Glock’s simplified firing assembly makes it uniquely susceptible to tampering.

The federal Bureau of Alcohol Tobacco and Firearms recovered more than 5,849 conversion devices between 2017 and 2021 – a 719% increase. In Connecticut, Hartford police seized 51 of them between 2023 and 2024.

The city’s suburbs have also seen a spike.

“Most people who have these conversion kits aren’t people who are getting their pistol permits,” said West Hartford police chief Vernon Riddick. “They’re people that are doing it for nefarious reasons to abscond and get around the law.”

Gov. Ned Lamont and the Connecticut Police Chiefs Association want to ban all “convertible pistol” sales until Glock changes its design. On Tuesday, the General Assembly’s Judiciary Committee advanced the proposal.

“Machine guns are illegal in the state of Connecticut. Yet certain manufacturers of pistols and other firearms are circumventing that prohibition,” said state Rep. Steve Stafstrom (D-Bridgeport), the committee’s co-chair.

Gun owners could keep the Glocks they already own, but new ones would be outlawed. But opponents said the bill is vague and could place almost any handgun owner in legal jeopardy.

“All of my semi-automatic long guns are capable of being converted. None of them have been,” said state Rep. Craig Fishbein (R-Wallingford). “To point the finger at individuals that lawfully own firearms that are possibly able of conversion, I don’t think is a proper public policy.”

“It’s unconstitutional,” added state Rep. Doug Dubitsky (R-Chaplin). “Glock is the most commonly used and possessed handgun in the state and in the nation for self-defense.”

The National Rifle Association is challenging a similar law in California. New York and several other states are considering bans of Glock sales, and Sen. Richard Blumenthal is pushing for more money for the ATF in Congress.

Glock did not respond to a request comment. Experts have noted that redesigning their pistols would be expensive – but Stafstrom said it’s possible.

“The bill attempts to change that by asking those manufacturers to change their model, which they have done elsewhere,” he said.

The legislation now heads to the full Connecticut House of Representatives.