I did some diggin and found some info specifically mentioning the xtra full turkey choke. As long as its copper plated lead, there should be no issue at all. The plated lead shot is still soft enough to be safely fired through the choke. There was a time when steel shot was ruining choke tubes, but these chokes were made before the steel shot and not designed to handle the pressure. In fact steel is not recommended in anything tighter than modified. Since the developement of steel shot, choke tubes have been designated for one or the other or in some cases both.
I have read of chokes designed to handle steel that have still cracked under pressure, typically steel used in a full choke.
Copper plated lead shot, like a turkey load will be fine, steel can bulge the barrel or rings or even shred a choke tube. The other side of this is that steel doesnt pattern very well I'm told through a full or xtra full choke.
What size shot are you planning to use?