New Jersey is looking to become the second U.S. state to outlaw a powerful gun that critics say can be used by terrorists to shoot down an airliner.

Democratic lawmakers and Ceasefire NJ, an antigun group, unveiled a plan Monday to make it illegal to sell .50-caliber weapons in New Jersey.

California is the only state with a similar law. Maryland strictly regulates the rifle by requiring enhanced background checks and other requirements for its purchase, according to Legal Community Against Violence, a public interest law center that favors gun control.

Supporters argue the guns are inappropriate for civilian use because they can fire armor-piercing rounds that can penetrate and ignite chemical plants, refineries and rail tank cars. The guns, which resemble large hunting rifles, are accurate up to 1.5 miles.

"We can wait for the first time mayhem occurs in our country before we ban civilian sale of these weapons," said Bryan Miller, Ceasefire NJ executive director, "but then dozens of people will likely have died."

Gregory Paw, director of the New Jersey Division of Criminal Justice, endorsed the legislation. Paw spent 11 months in Iraq advising the new Iraqi government in its war crimes cases against Saddam Hussein, and said there were documented attacks by insurgents with .50-caliber weapons.

"The only thing that comes out of this weapon is evil," Paw said.

Gun rights advocates planned to fight the proposal.

"This gun ban legislation will not reduce crime because it mistakenly targets the tool rather than the criminal, and the criminal mind will always find another tool," said Scott L. Bach, president of the Association of New Jersey Rifle & Pistol Clubs.

Assemblyman Reed Gusciora, among the bill sponsors, said he hoped to see hearings in the coming weeks on banning the weapon, which he said could cause major worries if they fell into the hands of criminal street gangs.

"These guns serve no useful purpose," he said.

New Jersey legislators want to include .50-caliber weapons in the same law that bans explosive devices. Violators would face up to five years in prison and a fine up to $15,000. The proposal would exempt antique guns and traditional rifles that fire a single shot. It would also allow people who own a .50-caliber weapon before the law takes effect to keep their weapon.

Still, Bach's organization, which represents the National Rifle Association in New Jersey, said the law was misguided.

Because of their unwieldy size, heavy weight and $3,000-$10,000 price tag, he said, "modern .50-caliber rifles are hardly the choice of criminals."