You might not know the names Christina-Taylor Green or Melinda Herman, but their stories dramatically define the emotionally charged debate over high-capacity ammunition magazines.

A student council member at her elementary school, Christina-Taylor, 9, was waiting to meet Rep. Gabrielle Giffords at a Tucson, Ariz., shopping plaza when Jared Loughner opened fire with a Glock 19 semi-automatic handgun equipped with a 33-round magazine, killing six and wounding 13, including the congresswoman.

Loughner’s 13th shot ripped through Christina-Taylor’s torso, lethally tearing her aorta and several organs. Twenty shots later, Loughner was tackled while trying to reload.

On the other side of the debate is Herman, a 37-year-old suburban Atlanta housewife who protected her two children from a crowbar-wielding intruder in their home last month by emptying her six-shot .38-caliber revolver. Despite being hit five times, the man managed to flee.

Whether there should be a nationwide limit on the number of bullets in a magazine is a question dividing Americans after the Newtown, Conn., school massacre. The idea of a limit has picked up momentum on Capitol Hill. But deciding where to draw the line is proving difficult.

Are 10 bullets — the limit in California and the number backed by many U.S. lawmakers and the White House — enough? Or should it be 15, the number of rounds police generally carry in their handguns? Do hunters, target shooters or even mothers protecting their children need more?

The Senate Judiciary Committee on Wednesday will grapple with those questions when the panel holds its first hearing on a bill by U.S. Sen. Dianne Feinstein, D-Calif., that would ban 157 specific models of military-style assault weapons and magazines that hold more than 10 rounds of ammunition.

Two arguments

Retired astronaut and gun owner Mark Kelly, Giffords’ husband, testified to Congress last month that if Loughner had been tackled while trying to reload after 10 rounds, Christina-Taylor “would be alive today.”

On the flip side, had Herman’s wounded assailant attacked her and her kids instead of fleeing — or had he come with an accomplice — she would have needed more ammo.

“This president wants to take away people’s rights to own the appropriate tool to repel an invader or invaders into their houses,” conservative radio host Lars Larson argued recently on Fox News.

For now, most Americans disagree with Larson. A CBS News poll conducted Feb. 6-10 found 59 percent of Americans favor a ban on high-capacity magazines. A new Field Poll shows 58 percent of California voters feel the state should outlaw the possession — not just the sale and manufacture — of magazines with more than 10 rounds.

The public support could mean that limiting the size of magazines is one of two key proposals — the other being expanded background checks for gun purchases, similar to what California already has — with the best chance of getting through Congress. Some gun-friendly Democrats who won’t vote to outlaw assault weapons have indicated they’re open to banning high-capacity magazines.

“Requiring a shooter to reload can provide critical seconds — seconds for law enforcement to intervene, seconds for people to get away, seconds for people like those who tackled the shooter in Tucson,” said Ben Van Houten, managing attorney at the San Francisco-based Law Center to Prevent Gun Violence.

Magazines with more than 10 rounds were banned nationwide under the 1994 assault weapons ban. But Congress allowed that law to expire in 2004.

The main reason for the renewed attention on high-capacity magazines is their use in most of the latest mass shootings.

In July, authorities say, James Holmes, using a 100-round drum magazine for his semi-automatic rifle as well as a shotgun and a handgun with its own extended magazine, shot 70 people — killing 12 — in less than 90 seconds in an Aurora, Colo., movie theater. Those 100-round drums can be bought for as little as $139.99 and are illegal only in six states, including California, and the District of Columbia.

In the Connecticut shooting, Adam Lanza fired an estimated 150 shots using 30-round magazines, which come standard with the .223-caliber Bushmaster semi-automatic rifle he carried.

Law is hard to assess

It’s been hard to measure the effectiveness of California’s 10-round limit. Those who owned larger-capacity magazines before the 2000 ban were allowed to keep them, and it’s still easy to buy bigger magazines in Nevada, Arizona, Oregon and most other states, with no ID required.

Nationwide, about 40 million such magazines are believed to be in circulation, and none of the bills now under consideration in Congress would require giving those up. So any “ban” would take a long time to produce a significant effect for a problem some say is peaking now.

“In the past two years we’ve seen a rise in large-capacity magazines for handguns,” said Oakland police Officer David Wong, who is in charge of checking and cataloging firearms his department seizes.

Wong estimated that about a sixth of the handguns seized in Oakland are equipped with high-capacity magazines, and they’re not old ones that predate California’s ban. “These are new magazines; we’ve taken them apart and examined the internals,” he said, indicating that they’re almost certainly coming in from other states.

A 2004 report for the National Institute of Justice that studied the impact of the 1994 assault weapons ban concluded that guns equipped with high-capacity magazines accounted for a disproportionate share of guns used in mass shootings and the killing of police officers.

One of the shootings that inspired the assault weapons ban happened in San Francisco in 1993, when Gian Luigi Ferri used a pair of Intratec TEC-DC9 9 mm handguns fitted with 50-round magazines, as well as a .45-caliber pistol, during his rampage through law offices at 101 California St., killing eight and wounding six.

Among those Ferri killed was attorney Jack Berman, whose wife, Carol Kingley, of San Francisco, says a renewed limit is long overdue. “I don’t think we can just afford to throw up our hands and say there are so many out there that we can’t do anything,” she said.

Gun owners in California, who have lived with the 10-round limit for more than a dozen years, have a range of opinions about the proposed national restrictions.

Wilderness Unlimited CEO Rick Copeland, whose Hayward-based private hunting club has properties across California and Oregon, said he has grown accustomed to the limit and it doesn’t impede his hunting. But, he said, that doesn’t make it right.

“Creating laws that don’t change anything is just a big waste of time,” he said, adding that he’d rather see the state repeal its limit than see the nation adopt it.

Fear of criminals

Gun owner Kevin Silver, a 47-year-old tech executive from San Jose, admits “10 rounds is satisfactory for me in recreational, hunting and defense situations,” but he said a 10-round nationwide limit on magazines wouldn’t do much to reduce gun crime or lower the body count at mass shootings. Besides, “if something like the L.A. riots broke out in my neighborhood, I would definitely want to have access to a few 30-round clips to protect my family and neighbors,” said Silver, quickly acknowledging that the comment might sound extreme.

Fellow gun owner John Simutis, of Concord, said from a self-defense perspective, police are probably the best judges of what magazine size is appropriate — and they’ve chosen to carry 15-round magazines.

Civilians should have the right to be as well armed as the police, said Simutis, 63, a retired nurse and computer programmer.

“I deserve the same chance the police have,” he said. “My life is just as valuable to me as an officer’s life is to him or her.”

Josh Richman covers politics. Contact him at 510-208-6428. Follow him at Twitter.com/josh_richman. Read the Political Blotter at IBAbuzz.com/politics.