Dennis Burke, the U.S. attorney for Arizona, says the ring is believed to have supplied the Sinaloa cartel with guns.
Authorities say some of the weapons were used in shootings in Mexico's drug war.
Burke says those indicted include ring organizers and "straw buyers" recruited to buy guns on behalf of smugglers.
Officials say one buyer who is accused of making six buys for the ring purchased 48 guns.
In all, 560 of the ring's guns were recovered, a third in Mexico and the rest mostly in Arizona.
The indictment was unsealed Tuesday and will likely renew the nation's gun law debate in the wake of the Tucson shooting of Rep. Gabrielle Giffords.
According to MSNBC, officials said the alleged "straw buyers" had no trouble buying the guns and passing federal background checks despite buying multiple firearms and spending large amounts of cash. In one case, seven people spent $104,251 in cash at several Phoenix-area dealers to purchase 140 firearms, according to officials.