According to the ATF database, there are 6 registered FFLs in Harrisburg, Illinois.
5 S MAIN ST STE #3HARRISBURG, IL, 62946
701 N COMMERCIAL STHARRISBURG, IL, 62946
4755 HWY 34 SOUTHHARRISBURG, IL, 62946
816 W ROBINSON STHARRISBURG, IL, 62946
1325 SOUTH LEDFORD STHARRISBURG, IL, 62946
710 S COMMERCIAL STHARRISBURG, IL, 62946