A federal law banning plastic guns is set to expire next month, unless Congress does something about it, which, knowing Congress, would really be something.

Currently, under the Undetectable Firearms Act, it is illegal to own, sell or manufacture any firearm that cannot be picked up by metal detectors; that law expires on December 9th, and supporters are concerned our calamitous Congress will fail to act quickly enough to renew it. "We’re on the clock, and as we know, this Congress doesn’t deal well with deadlines,” Dan Gross, president of the president of the Brady Campaign to Prevent Gun Violence, told the Times. What on earth could have given him that idea?

The expiration of the law is particularly concerning in light of the proliferation of 3-D plastic printer guns. The guns are legal as long as manufacturers add some detachable metal to them, technically making them detectable through screeners. But officials are considering extending the Undetectable Firearms Act and adding new amendments to include provisions to help curb the spread of the weapons, which are cheap and downloadable.

Unsurprisingly, a number of pro-gun advocates are against such an extension. "They’re not going to be in Kinkos,” Larry Pratt, the executive director of Gun Owners of America, said of 3-D weapons. “And at the moment, they can’t fire that many rounds. It’s just not something that we’re going to be dealing with anytime soon.” A 3D gun being manufactured now fires a standard .380 handgun round; it can also be used with a silencer.

The National Rifle Association has stayed surprisingly silent on this issue, but last week, Philadelphia's City Council voted to ban the use of 3-D printers to make weapons unless that person possessed a firearm manufacturing license. And in May, the world's first 3-D plastic printer gun, dubbed The Liberator, was downloaded 100,000 times for free. Eventually, though, the State Department forced the company behind the gun to close up the file.