Through last week, the city reported 409 homicides this year compared to 324 during the same period in 2011. Although the violence still doesn't approach the nearly 900 homicides a year Chicago averaged in the 1990s, officials say gang activity was largely to blame for a rash of shootings earlier this year.
Preckwinkle insists the ordinance is far more about addressing gun violence than raising money for a county that faces a deficit of more than $100 million next year.
"The violence in Cook County is devastating and the wide availability of ammunition only exacerbates the problem," she told the board Thursday.
Dave Workman, of the Citizens Committee for the Right to Bear Arms, said the tax is sure to infuriate gun-rights advocates when they hear about it.
"It's not the law-abiding citizens stacking bodies like cordwood in Chicago; it's the bad guys," he said.
Preckwinkle sought to fend off that argument during her remarks Thursday. She said nearly a third of the guns recovered by police after being used in Chicago crimes had been purchased legally, initially at least, in suburban Cook County.
Earlier this week during a meeting with a newspaper editor board, Preckwinkle called the county's legal gun shops "a conduit for crimes in Chicago," according to a transcript released by her office.
Neither Preckwinkle spokeswoman Kristen Mack nor a National Rifle Association spokesman knew of any other local jurisdiction in the nation that has imposed a tax on bullets, even though some have considered it. Legislation on such a tax was previously introduced by state lawmakers in Springfield, but it was never been voted on, Mack said.
Gun rights advocates from around the country who watched closely as Chicago's handgun ban made its way through the courts, culminating in a U.S. Supreme Court decision in 2010 to overturn it, say this proposal has definitely caught their attention.
"Eyes are on Chicago and Illinois right now," said Andrew Arulanandam, a NRA spokesman.
Richard Pearson, executive director of the Illinois State Rifle Association, predicted the effort would "drive business out of Cook County" and into other counties and bordering states, such as Indiana and Wisconsin.
One suburban gun shop owner agreed, saying that his customers, many of whom are hunters, will simply go elsewhere.
"Who's going to come to Tinley Park to buy ammunition," said Fred Lutger, the owner of Freddie Bear Sport in that suburban Chicago community.
As for the money going toward treating gunshot victims, Lutger said, "Why should we be paying for gang bangers shooting each other?"
Some members of the county board that will be asked to approve the budget have expressed skepticism about whether the tax would raise as much money as Preckwinkle expects because it would simply prompt consumers to go elsewhere for their bullets and firearms.
Commissioner John Fritchey questioned whether county was simply setting itself up for a lawsuit that will cost the county more money than the tax will bring in. He also wondered if it would have any role in reducing crime.
"I don't think a nickel a bullet will cause a shooter to rethink pulling the trigger," he said.
Workman predicted a public outcry against Preckwinkle's motivation for proposing the measure.
"I could envision a coalition of different groups saying, 'Wait a minute, you are making us financially responsible for the Cook County government's inability to hold down spending?" he said.
While Arulanandam promised that the NRA "will jump on this issue," and perhaps sue, Preckwinkle said she wasn't worried about a lawsuit.
"You're welcome to sue," she said. "We've looked at this and we believe we can survive any challenge."