Officials say the Chicago man had been identified as a possible threat to federal and Cook County judges, and investigators also found a list of court workers - some with bull's-eyes next to them.
The cache of weapons was discovered over the weekend. Cook County Sheriff Tom Dart and federal authorities displayed the weapons at a news conference Monday.
Authorities say Kevin Long was charged with unlawful use of a weapon by a convicted felon after last week's arrest, and Dart says at least another 46 counts are pending - with more charges possible.