Who’d have thought it? The House of Representatives has voted to extend the soon-to-expire ban on undetectable plastic guns. In doing so it did two favors for Americans, protecting them against a real threat to safety and also demonstrating that gun control is possible, despite the howling of those who think the Second Amendment offers blanket immunity from any effort to restrict firearms.

The Senate has yet to act on this law, though it is expected to support it. The need is obvious. It is now possible to make plastic handguns with 3-D printers that can potentially slip past metal detectors and fire lethal rounds. True, the device is cost-prohibitive for average consumers but, just as priceds fell for flat screen televisions, DVD players and other technology, the will here, as well.

Wouldn’t it make sense to have legislation on the books that keeps up with changing conditions? Congress first passed the Undetectable Firearms Act in 1988. It was signed by President Ronald Reagan.

The legislation, renewed twice since enacted, bans guns that can pass unnoticed through a metal detector. The new House law simply extends the current ban, rather than amending it to bring it up to speed by banning production of plastic weapons with 3-D printers. That would have been preferable, but renewal was the urgent matter.

Sens. Charles E. Schumer, D-N.Y., and Bill Nelson, D-Fla., are leading the effort in the Senate, with Sen. Kirsten E. Gillibrand, D-N.Y. as a co-sponsor. There, the debate continues to include the 3-D printer restriction.

At a recent media briefing, senior officials of the Bureau of Alcohol, Tobacco, Firearms and Explosives said they had built and tested the Liberator, a printed handgun designed by Defense Distributed, a Texas organization cofounded by a former law student. The Liberator’s designs were downloaded more than 100,000 times in just two days before federal officials demanded the plug pulled in May.

One could debate design and efficacy. Some say 3-D is just a fad and others doubt the consistent accuracy of the shot. But it only takes one on-target shot to make a deadly difference and getting there can be made easier if the firearms go undetected.

Legally, manufacturers of 3-D printed guns have to make their firearms detectable to security screeners in some way. They usually include some form of metal, which can be nonfunctional and easily removable. And who’s to say technological advances won’t include plastic bullets?

Technology is on the move. It isn’t stopping. And neither will improvements in 3-D printing. The law needs to be renewed; extended would be better.