Keane, whose group includes manufacturers, said the reports of massive federal purchases were not true.
The government routinely buys products in bulk to reduce costs, and Homeland Security has said the latest purchases are no different.
Last year, the department put out bids for a total of about 1.6 billion rounds of ammunition over the next five years. The rounds are to be used for training, routine weapons qualification exercises and normal duty by various department agencies.
On a smaller scale, some local law enforcement agencies are also having problems getting ammo.
Jennifer Donnals, a spokeswoman for the Tennessee Highway Patrol, said the agency was still waiting on rifle and shotgun ammunition ordered in November.
In Phoenix, the Police Department has stopped providing officers with 100 rounds of ammunition per month for practice. Sgt. Trent Crump said 10 to 15 percent of the department's 3,000 officers, who are assigned .40-caliber and .45-caliber handguns, had taken advantage of the ammunition for practice shooting.
In January, police chiefs in central Texas said they were having trouble arming their officers because of shortages of assault rifles and ammunition.
The major U.S. manufacturers are running shifts around the clock to try to meet increased demand, Keane said. The foundation projected $1.5 billion from ammunition sales in 2011 and $2.8 billion from gun sales, totals that more than doubled in a decade.
Stockpiling has also been fueled by false online rumors, such as one that purports a coming nickel tax on each bullet, which would triple the cost of a .22-caliber cartridge, said Hans Farnung, president of Beikirch's Ammunition, a retailer and wholesaler in Rochester, N.Y., that sells in seven states.
"I don't want to call them doomsdayers, but people get on these blogs on the Internet and they drive people's fears," he said. "They do not want to wait around and see."
The tax rumor was fueled by proposals in Connecticut, California and Illinois that haven't advanced.
This isn't the first U.S. run on ammunition. Walmart's Kory Lundberg said the retail chain previously rationed in 2009, the year Obama entered the White House. However, sportsmen and tradesmen say the current shortages are nationwide, and the worst they've seen.
New York's law will require ammunition sellers to register and buyers to undergo a background check starting Jan. 15, 2014. Richard Aborn, president of the Citizens Crime Commission of New York City, said the run on guns and ammunition isn't surprising and is fueled by "gross exaggerations," when reasonable discussion is what's needed.
Bruce Martindale, a champion marksman from upstate New York who normally uses .22-caliber rimfire ammunition, said it's now hard for him to get anything, partly because online retailers are reluctant to ship to New York and risk running afoul of its new law.
"I can't buy supplies anywhere," he said. Like many competitors, he has cut back on practice but says he doesn't see a public safety concern.
"This is legitimate gun owners buying," he said. "I don't think criminals are stockpiling."