According to authorities, Trung Huynh lives across the street from an elementary school in Murrieta.
Investigators said he used an Arizona ID card and post office box to buy the weapons including four AK-47s. In addition, officials found three 9-mm pistols and more than 1,000 rounds of ammunition in a gun safe.
The arrest followed a tip from federal agents who had seen Huynh at a gun show in Arizona.
Huynh was released Friday after posting $25,000 bail.
The Associated Press contributed to this report.