No, the mags aren't illegal.  It's inserting the mag into a semi-auto gun that makes it an "automatic weapon" per ORC.   ORC 2923.11 "“Automatic firearm” means any firearm designed or specially adapted to fire a succession of cartridges with a single function of the trigger. “Automatic firearm” also means any semi-automatic firearm designed or specially adapted to fire more than thirty-one cartridges without reloading, other than a firearm chambering only .22 caliber short, long, or long-rifle cartridges."  Insert 40rd AK mag into AK,  its now been adapted to fire more than 31 rds regardless of how many you load. The law says adapted not capable.