It might have been more difficult for Jared Lee Loughner to purchase the 31-round magazine authorities said he used in Saturday's mass shooting if a federal law that expired in 2004 were still in effect, a gun-control advocate said.

From 1994 to 2004 under the Federal Assault Weapons Ban, the manufacture of magazines with more than 10 rounds was banned. Even though existing magazines were grandfathered in and still legal to buy, the supply was dwindling when the ban expired in 2004, said Kristen Rand, legislative director for the Violence Policy Center, a Washington, D.C.-based gun control group.

Gun advocates don't agree, saying Loughner would have had no problem finding a high-capacity magazine even if the law was still in place.

Rand and a Democratic legislator from New York who is promising legislation to ban the sale of high-capacity magazines to anyone not in law enforcement or the military believe fewer people would have been killed and wounded Saturday if Loughner had fewer rounds in the magazine.

"The less bullets you have, the fewer victims you can shoot," said U.S. Rep. Carolyn McCarthy, D-N.Y.

Authorities say Loughner used a Glock semiautomatic pistol with an extended magazine, also known as a high-capacity magazine.

Investigators found 31 shell casings at the scene and an empty magazine that held 31 rounds, said Pima County sheriff's spokeswoman Deputy Erin Gibson.

Loughner was tackled by four people before he could load another magazine. Investigators found three other unused magazines, including one other high-capacity magazine with 31 rounds, Gibson said.

A standard magazine for a 9mm Glock semiautomatic pistol holds between 13 and 17 rounds, according to the Glock website.

McCarthy's office is still discussing the details of the legislation, including how many rounds would be defined as high-capacity.

There are multiple problems with McCarthy's proposed legislation, said Charles Heller, co-founder and secretary of the Arizona Citizens Defense League, a pro-gun-rights group.

First, it punishes law-abiding gun owners for the acts of criminals. Secondly, there's no way to remove all the high-capacity magazines from the market.

Third, it doesn't make sense, Heller said. A gunman can carry two guns if he wants more rounds and get the same number of shots off, said Heller, who himself often carries two guns.

"So, great, you reduce the capacity from 33 down to 19 and you are telling me that is going to change something?" Heller said. "What rational person thinks that's the solution?"

The only way to prevent future mass shootings is make sure more people are armed and trained to defend themselves, Heller said. He's proposing a plan to open up Department of Public Safety facilities to arm and train legislators and their staffs.

"You cannot stop this from happening but what you can do is, when it happens, you can address it at the scene," Heller said. "The only way they would think twice about it is if there was a body of armed men."

The National Rifle Association wouldn't comment on the proposed legislation, only sending this e-mailed statement: "At this time anything other than prayers for the victims and their families would be inappropriate."

Rand said the fact that Loughner didn't break any law when he bought the Glock at the Sportsman's Warehouse near his home Nov. 30 and when he purchased the ammunition illustrates the overarching problem - it's simply too easy for people to get high-powered guns with plenty of ammunition.

The common thread in mass shootings is the use of high-capacity magazines, said Rand. The shooter in the 2007 Virginia Tech shooting that killed 32 also used a Glock with a high-capacity magazine, she said.

"What we are saying is let's at least start by ratcheting back that firepower," Rand said.

McCarthy, whose husband was killed and son wounded in a 1993 train shooting in Long Island, has been a champion of gun control issues for years.

Six states and the District of Columbia ban the sale of high-capacity gun magazines: California, Hawaii, Maryland, Massachusetts, New Jersey and New York.

Arizona is one of three states to allow people to carry a concealed gun without a permit. The others are Vermont and Alaska, Rand said.

Contact reporter Brady McCombs at 573-4213 or