I guess I have answered my own question... From Remington's Web site...

"Some turkey chokes, including the Extra Full with .040 inch of constriction available from Remington were designed for use with softer lead shot and should not be used with Hevi-Shot. If a choke was not designed to be used with steel shot or Hevi-Shot, it should not be used. For wingshooting, the more open chokes designed to handle steel have proven to be quite useful when using Hevi-Shot."

hmmm.... You think they should put this on the box or something!