From LA Times:

Ten special agents from the California Department of Justice were watching as a man walked out of the Big Reno Show and placed his purchases in his car.
The black Isuzu with California plates headed west on Interstate 80 into the Sierra Nevada, eventually crossing the Nevada state line. That’s when the California Highway Patrol pulled Vincent Huey over. Inside the vehicle, state Justice Department agents found 18 high-capacity magazines, some capable of holding 30 rounds, according to court records.