In this case this is a 1974 Tama Imperialstar King Beat, but was released soon after Star became Tama, the mechanism still had the Star logo and triple flange hoops, late 1975 they changed the casts and had Tama logo on the mechanism and changed to die cast hoops.As to COB, I don't know. I never tried a magnet on the shell yet.
+1.Those imperialstar badged steel shelled drums were either the Kingbeat or Powerline,which had a different strainer.The shells are heavy chrome over steel,one piece.They weren't COB.The lugs weren't the best so,they will crack under high tension.Thhey are great sounding drums,and with diecast hoops,sound like gunfire if you play rimshots on them.
Steve B