"The first Assault Weapons Ban was just starting to show an effect when the NRA stymied its reauthorization in 2004."
Reauthorization of the 1994 Assault Weapon Ban was stymied because even its supporters (other than the most fanatical antigun types) saw that it did little or no good, was symbolic with little effect, and may have diverted federal law enforcement funds from more productive programs.
As the sunset of the AWB approached, CDC 2003 and NRC 2004 reviews of research into gun violence and gun laws found no measurable benefit from the AWB. When 2004 approached, Congress did not have the votes to renew the AWB even though George W. Bush said he would sign it if Congress sent the renewal to his desk.
The uselessness of the AWB was recognized way before 2004 by people who could not honestly be labeled gun rights or NRA supporters. The New York publisher of Harper's Magazine was in my hometown on business in 1999 and stayed at the convention center the weekend of the gunshow. He wrote an op-ed that ran in the local paper as "A Northerner's fear and loathing in Kingsport".* In calling for banning handguns in exchange for no limits on long arms, he observed "I'm sure the legalization of assault rifles would upset a few liberals, but they well understand that most gun violence is wreaked by hidden pistols... And they know that maintaining the ban on assault rifles is mere window-dressing, just a dodge for politicians like President Clinton who want to play both sides of the fence."
It was kinda funny he called for us to give up our handguns after noting "I live in one of the most violent cities in America -- New York -- where children carry guns and use them to redress frivolous slights, while the police are among the most trigger-happy in the nation." That's testimony we need a national version of New York's Sullivan Act... not. (The year the op-ed appeared, Kingsport had gone 3 years without a homicide and Sullivan County had had a year with no murders. A 150,000 population sample of NYC 1999 would have had more than zero homicides.)
According to the FBI Uniform Crime Report breakdown of weapons used in murder, you are more likely to be killed by an unarmed attacker using his "personal weapons" (hands, feet, etc) than by an attacker using an assault weapon (military style long gun). The money spent on enforcing an assault weapon ban would be better spendt identifying and treating the mentall ill or used to target criminals, not gun owners.
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* John R. MacArthur, "My compromise in the gun debate", The Providence Journal, July 5, 2000,
http://www.highbeam.com/doc/1G1-63162862.html
Unfortunately the Highbeam Research link requires subscription for the full article.