WASHINGTON -- Online rumors about a big government munitions purchase are true, sort of.The Homeland Security Department wants to buy more than 1.6 billion rounds of ammunition in the next four or five years. It says it needs them -- roughly the equivalent of five bullets for every person in the United States -- for law enforcement agents in training and on duty.Published federal notices about the ammo buy have agitated conspiracy theorists since fall. That's when conservative radio host Alex Jones spoke of an "arms race against the American people" and said the government was "gearing up for total collapse; they're gearing up for huge wars."The government's explanation is much less sinister.Federal solicitations to buy the bullets are known as "strategic sourcing contracts," which help the government get a low price for a big purchase, said Peggy Dixon, spokeswoman for the Federal Law Enforcement Training Center in Glynco, Ga .The training center and others like it run by the Homeland Security Department use as many as 15 million rounds every year, mostly on shooting ranges and in exercises.Dixon said one of the contracts would allow Homeland Security to buy 750 million rounds of ammunition over the next five years for its training facilities. The rounds are used for basic and advanced training for federal law enforcement agencies under the department's umbrella.The facilities also offer firearms training to tens of thousands of federal law officers.The rest of the 1.6 billion rounds of ammunition would be purchased by Immigration and Customs Enforcement, the federal government's second-largest criminal investigative agency.