When using steel shot, or any shot similar to steel, such as TSS or Bismuth, you should only use stainless steel choke tubes with modified or more open chokes. You should not use steel shot with Extra Full, Full, or Improved Modified Chokes of any kind.
If it is a fixed choke barrel, we do not recommend using steel shot, as it may damage your barrel(s). You may have fixed chokes on the older Centurion I, Centurion II, Orion, Athena, and Model 82 Shotguns.