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.