A large capacity magazine is any ammunition feeding device for use in a firearm that can hold more than 10 rounds of ammunition. Thus a magazine made prior to the 1994 ban and holding 12 rounds of ammunition is deemed dangerous, while its post-ban counterpart which holds 10 rounds is completely safe.

So called "high capacity" magazines are labeled as such by anti-gun organizations and others with anti-gun agendas to instill fear of such things, when in reality one could reload a weapon with multiple smaller capacity magazines with ease for the same effective capacity. Many guns are designed to hold more than 10 rounds of ammunition, and because of the 1994 law are required to be restricted to 10 rounds. In reality "large capacity" should be called "full capacity".

In 1994, it became illegal in the United States to manufacture a full capacity magazine except for sale to government or law enforcement agencies, and it is illegal for a private citizen to possess a post-1994 full capacity magazine, as identified by a required engraving on the magazine that says "Restricted: Government/Law Enforcement use only."

It is still legal for a person to possess a "pre-ban" full capacity magazine.

See also: Assault weapons ban (USA)