ICORE has two types of courses of fire. Shots Limited or Shots Unlimited. It doesn't have any rules specifically governing steel challenge type stages. It has rules (6.6.10. Failure to hit a Stop Plate and 188.8.131.52. Covering FTE's on a steel-only stage) that apply to steel challenge type stages, but doesn't have a rule governing what a steel challenge stage is. Find an example in the rules that allows throwing out the worst string. You won't. That being said, the BOD didn't want to enact rules to govern steel challenge type stages. The idea is to give Match Directors total control over them. You won't find a rule that says hitting the stop plate ends the string. You will find a rule that allows shooters to fire right up to the issuance of "If clear, close cylinder,holster". So what happens if a shooter missed a plate but hit the stop plate afterwards? Did the string stop when the stop plate was hit or can he take a makeup shot prior to "If clear, close cylinder, holster"? That's why the wording of Chapter 2 that covers the stage being explained by a complete written stage description is so important to these stages. I hope this explains my rationale more completely.