A bill that will be introduced in Congress next week would ban gun ammunition magazines with more than 10 rounds of ammunition.

The measure — from U.S. Rep. Carolyn McCarthy, D-N.Y. — comes on the heels of Saturday’s mass shooting in Tucson when the gunman fired 31 rounds from a 9mm Glock semiautomatic pistol, investigators say.

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

From 1994 to 2004 under the Federal Assault Weapons Ban, the manufacture of high-capacity magazines, defined as more than 10 rounds, was banned. But, existing magazines were grandfathered in and were still legal to sell and transfer.

McCarthy’s bill would go a step further — banning the manufacture, import, sale and transfer of magazines with more than 10 rounds, except for active law enforcement, retired law enforcement for magazines transferred to them at retirement, for testing or for the protection of nuclear materials.

People with high-capacity magazines purchased before the date of enactment of the law would be allowed to keep them, but not sell or transfer them.

McCarthy and other gun control advocates believe fewer people would have been killed and wounded Saturday if alleged shooter Jared Lee Loughner had fewer rounds in the magazine.

After firing the 31 shots from the first magazine, Loughner was tackled by four people before he could load another magazine, say investigators, who found three other unused magazines, including one other high-capacity magazine with 31 rounds, Gibson said.

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The bill wouldn’t prevent future mass shootings, said Charles Heller, co-founder and secretary of the Arizona Citizens Defense League, a pro-gun-rights group. A shooter could simply carry two guns and have the same number of rounds, he said.

The only way to prevent future mass shootings is to 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.

McCarthy’s bill is one of two being proposed in wake of the shooting that would establish more gun controls. Rep. Peter King, R-N.Y., is drafting a measure that would prohibit people from carrying guns within 1,000 feet of the president, members of Congress or federal judges.

Contact reporter Brady McCombs at 573-4213 or bmccombs@azstarnet.com.