Just as a point of information, I went to the Ruger site and here is part of their specifications sheet on the Red Label:
"** Factory steel-shot compatible chokes including Full, Modified, Improved Cylinder and two Skeet come with your Red Label and can be easily changed with the included choke tube wrench."
Obviously steel shot can be safely shot through this shotgun which should include the extra full since it does not specify lead only and their factory chokes are steel compatible. That still does not answer my original question: Is there an advantage to using the X-full?