Danny Morones, 28, the first of the so-called Fast and Furious defendants to be sentenced, drew a 57-month prison term Monday in the case tried in San Diego, the Los Angeles Times reported.
Morones pleaded guilty to acting as a "straw purchaser" of high-powered weapons, including AK-47 assault rifles, and to recruiting others to buy weapons.
The cases were moved to San Diego after the U.S. attorney's office in Phoenix recused itself.
Operation Fast and Furious was a failed gun-tracking operation run through the ATF's Phoenix office from 2009 until 2011. It allowed weapons to be illegally sold in the United States so they could be tracked across the U.S.-Mexican border to Mexican drug cartels, with the goal of arresting high-ranking cartel members. However, many weapons vanished.
Two weapons were recovered where a U.S. Border Patrol agent was shot and killed in December 2010. Other Fast and Furious weapons were found at crime scenes on both sides of the border.
The House Oversight and Government Reform Committee and the Justice Department's Inspector General investigated the failed operation, with the inspector general's report saying Fast and Furious posed a "significant danger to public safety."
Court documents indicated four AK-47s purchased by Morones were seized by Mexican military officers in September 2010, as well as six AK-47s bought by a Morones recruit also were seized.
Although gun purchases are legal in Arizona, it is illegal to buy them so they can be used by drug trafficking gangs and to lie on purchase documents, the Times said.