Schumer said plastic guns were "the thing of science fiction" when the ban was first passed in 1988 but such weapons are now a worrisome reality.
Brian Malte, a director of the Brady Campaign to Prevent Gun Violence, said his group's worries about the availability of plastic guns are "no reason to hold up renewal."
The use of 3-D printers to manufacture guns received heightened attention in May when Cody Wilson, then a University of Texas law student, posted blueprints online for using the printers to make the Liberator pistol, which he says he designed. Wilson, founder of Defense Distributed, a nonprofit that advocates the free distribution of information on 3-D printed weapons, was ordered by the State Department to take down the instructions after two days because of allegedly violating arms export controls, he said.
By then, the plans had already been downloaded more than 100,000 times and they remain available on file-sharing websites, he said.
"If you want to do this, it's plainly obvious there's no one standing between you, your computer and your 3-D printer. Anyone can make this gun," Wilson said Monday.
Lawmakers and law enforcement officials alike have long been concerned that technological advances could allow for the production of guns that don't have any metal, first passing the ban on such weapons in 1988 under President Ronald Reagan. It has been renewed twice since then.
Today 3-D printers can spray repeated, thin layers of plastic or other materials to create objects from toys to automobile parts to medical devices. They are being used increasingly by companies, researchers and hobbyists, and the technology is constantly improving.
But printing a gun isn't cheap. According to the Bureau of Alcohol, Tobacco, Firearms and Explosives said 3-D printers can cost anywhere from $1,000 to $500,000, though they can be rented. A traditional handgun can cost far less.
It's also unclear how effective such a gun can be.
ATF tested two plastic guns from different plastics earlier this year, and one of the weapons exploded when it was fired. The second one shot off eight rounds before ATF stopped the test.
Among the chief concerns from law enforcement and law makers has been that a 3-D printed gun, made of plastic or other materials, could be easily slipped through metal detector at a courthouse or other such facilities.
New technologies being used at airports, including back-scatter X-ray machines, are designed to detect non-metallic anomalies, such as liquids and potentially plastic guns.
While the NRA didn't oppose extending the current law, it has opposed expanding it, including applying the law "to magazines, gun parts, or the development of new technologies."
"We will continue to aggressively fight any expansion ... or any other proposal that would infringe on our Second Amendment rights," NRA spokesman Andrew Arulanandam said in a statement, referring to a provision in the U.S. Constitution that allows Americans to possess weapons. .
The conservative Gun Owners of America has opposed even the extension, saying such laws wouldn't stop criminals intent on printing weapons.
President Barack Obama and a host of lawmakers led by Schumer and other Democrats, have repeatedly pushed for changes to the nation's gun laws, including expanding background checks for gun buyers and other restrictions, since a shooting massacre at a school in Connecticut last Dec. 14. Twenty children and six adults were killed in a shooting carried out by a lone gunman who then shot himself to death.
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Associated Press writers Alan Fram and Henry C. Jackson contributed to this report.
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Follow Alicia A. Caldwell on Twitter at www.twitter.com/acaldwellap
