HACKENSACK – Metal detectors are designed to catch contraband – like guns.

But what happens if guns have no metal parts?

Rep. Josh Gottheimer discussed that very situation Thursday morning with local activists and law enforcement officials.

The congressman, like most Democrats, is a long-time supporter of what he calls “common sense” gun laws. Today’s event at the Bogota Savings Bank Center on the campus of Fairleigh Dickinson University was also geared to keeping firearms out of sporting venues, which Gottheimer said is a big concern with the FIFA World Cup coming to the U.S. in 2026. Eight matches, including the final, will be played in New Jersey, an event expected to attract more than a million people.

The particular issue revolves around the Undetectable Firearms Act, which dates back to 1988 and which was just renewed to run through 2031.

The act targets plastic weapons and other so-called “ghost guns” requiring that all guns include enough metal to set off X-ray machines and metal detectors.

Gottheimer explained that “enough metal” can be something as small as a marble.

The act has been renewed four times, but Gottheimer wants to stop the periodic renewal fight. He is proposing legislation to make the act permanent.

He said having the act on the books permanently is necessary, because criminals are becoming more creative in manufacturing guns with 3-D printers and the like that may not be picked up by a magnetometer. He said that since 2017, more than 37,000 ghost guns have been recovered by America’s law enforcement.

Gottheimer also said he plans to write to all the major professional sport leagues, and FIFA as well, urging them to support ways to keep firearms out of venues. He also is proposing that $620 million be appropriated for World Cup security.

Joining Gottheimer were representatives of Moms Demand Action, Bergen County Sheriff Anthony Cureton and Bergen County Prosecutor Mark Musella.

Referring to ghost guns and the like, Musella said:

“We cannot allow these guns to circulate in our communities.”

The CD-5 congressman said his proposal to make the act permanent should get bipartisan support, noting that “Gun violence kills Democrats and Republicans.”

That sounds good, but Gottheimer probably knows better.

The National Rifle Association and some other Second Amendment supporters reflexively oppose just about any restriction on firearms.

“This is a very tough issue,” Gottheimer said. “We never back down.”

The good news is that there is bipartisan support for Gottheimer’s proposed bill in both the House and Senate.