Adam Lanza, police say, used at least 150 bullets shot from an AR-15 assault-style rifle during his attack on the Sandy Hook Elementary School in Newtown, Conn., on Dec. 14 – killing 26 children and staff, and shocking the nation into a tumultuous debate over gun control.
Using the standard 30-bullet magazine that comes with the rifle, Mr. Lanza would have had to detach the springloaded magazines that pump each cartridge into the chamber only four times, as he fired relentlessly into two classrooms full of grade-school children. James Holmes, using a "drum magazine" that held 100 rounds, shot 70 people in an Aurora, Colo., theater in July in fewer than 90 seconds, police say.
That's why a ban on so-called "large-capacity" magazines is at the top of a gun control reform proposal by President Obama on Wednesday, which also includes banning assault-style rifles and beefing up background checks, among other actions.
The proposed ban on devices that are, in essence, small bullet-packed boxes with springs is an attempt to confront their popularity among gun enthusiasts. As New York Gov. Andrew Cuomo (D) questioned: Who needs more than seven bullets to kill a dear? Advocates of a ban say the ubiquity of large-capacity magazines contributes to bloodshed.
But gun rights activists challenge whether banning high-capacity magazines will reduce lethality in mass shooter-type situations. They question whether the ultimate motivation for regulating how many bullets Americans can jam into their guns at one time is to make criminals out of lawful rifle owners – and, eventually, to make standard handguns harder legally to use for self-defense.
Here's a primer on the current state of law on high-capacity ammunition magazines and how that might change with the new regulations proposed by Mr. Obama.
What is a 'high-capacity' magazine, and how many are in circulation?
Guns such as the AR-15 rifle and the Glock 17 pistol have magazines, or springloaded cartridge feeding devices, that hold more than 10 bullets, the limit proposed by Obama. Those magazines were technically illegal during the 1994-2004 assault weapons ban. (Several loopholes allowed manufacturers to make cosmetic changes to keep some versions legal.)
Gun control advocates such as Governor Cuomo, who on Jan. 15 signed the nation's first post-Newtown gun restrictions, suggest that regular Americans don't need the ability to shoot large numbers of continuous bullets for hunting or standard self-defense. Gun rights advocates say that it's not up to the government to decide what gun owners need for self-protection, and that new laws would only serve to criminalize lawful gun owners, while criminals would get hold of illegal magazines and guns anyway.
Experts estimate that as many as 40 million high-capacity magazines may be in circulation today in the US.
Have "high-capacity" magazine bans worked before?
While task forces concluded that the 1994 assault-weapons ban and bans on large-capacity magazines didn't noticeably effect violent-crime rates or mass shootings in the US either way, some evidence does show that such set-ups were used fewer times during the commission of crimes in some US cities during the 10-year span of the ban.
Studies have also found that casualty rates of mass shootings have increased after the assault weapons ban expired in 2004. Police in Virginia, for example, found far fewer high-capacity magazines at crime scenes in 2004 than they did in 2010. Gun critics point to those statistics to argue that larger magazines contribute to greater bloodshed.
What would the Obama plan do?
Obama's proposal bans high-capacity magazines with more than 10 rounds. To what extent currently owned magazines would be "grandfathered" or legalized, and whether people using them would have to register with the federal government, is not yet clear.
However a Senate bill sponsored by Sen. Dianne Feinstein (D) of California would ban dozens of guns as well as require gun owners to register "grandfathered" weapons and magazines in a national registry. Other proposals suggest that grandfathered weapons and magazines would have to be re-registered every five years.
Gun control advocates say smaller magazines would increase chances that bystanders, victims, or law enforcement officials could disrupt a mass shooting. During the shooting in Tuscon two years ago, gunman Jared Loughner was tackled to the ground as he tried to reload after firing 30 shots, killing six people and injuring then-Congresswoman Gabrielle Giffords.
Would the magazine ban become a de facto handgun ban?
The administration has said it has no designs on limiting people's ability to hunt or own guns for home protection. But gun rights advocates argue that if the ban on high-capacity magazine goes into effect, many handguns that are not explicitly prohibited in the president's proposal could become illegal.
Gun Owners of America says up to 80 percent of US handguns and 50 percent of all long rifles could become suddenly suspect under Obama's proposal, largely because of the magazine issue. The popular Glock 17 handgun, for example, has a 17-bullet magazine. Glocks are among the nation's most popular self-defense handgun, and also rank among guns used most often in gun violence.
"Depending on whether they grandfather, lots of gun owners won't be able use their Glocks, since the magazine ban goes to most Glocks," says Michael Hammond, legislative consultant for the conservative Gun Owners of America organization in Springfield, Va.
Gun rights advocates also point to a recent case in Georgia, where a mom with twins fought off an intruder by shooting all six bullets from a snubnosed revolver. While she hit the intruder five times, he was still able to flee and get into his car before he was found by police.
"Why should she have been limited to just those six or seven rounds?" wonders Larry Ward, founder of this Saturday's first-ever Gun Appreciation Day.
Nevertheless, Robert Levy, a conservative lawyer who helped win the landmark District of Columbia v. Heller gun rights case in 2008, says one reason the Obama administration is proposing a large-capacity magazine ban is because it's likely to be upheld in the courts.
"I can imagine a shop owner in the midst of a riot and he says he needs multiple rounds to protect his store and family," Mr. Levy told the Washington Post recently. "I can also imagine the multi-victim killings like we had in Newtown where there's a reasonable argument that innocent lives might have been saved if these magazines had been banned and if the ban had been effective. So I think if government can show … the benefits of banning high-capacity magazines, then I have no doubt that such a ban would survive a court challenge."