There seems to be some confusion over what happens if a competitor in a steel challenge match reacts to the start signal, i.e., mounts the gun toward the target, pulls the trigger, etc., and nothing happens. It seems to be a fairly common idea that this competitor gets to restart that string, but there are no rules to support this action.
If a competitor makes their attempt at a course of fire: draws a handgun, or brings a PCC or rimfire gun to bear on the targets in response to the start signal and the gun doesn’t fire, they are always free to correct the problem and continue. The problem may be that they didn’t load the chamber (this is a competitor issue, not an RO issue, see 8.1 in the SCSA rules), or the round simply doesn’t go off, or the gun is broken. In all cases, it’s up to the competitor to solve the problem. If they can’t, or they simply stop, a 30 second time should be recorded because they did not hit the stop plate (9.4). Again, there is no rule that supports allowing a competitor to restart or reshoot that string, once they’ve made their attempt at it. Rule 5.6 covers equipment malfunctions and specifically states that the string will be scored. If the gun can’t be repaired at that time, the competitor may retire once the gun has been cleared and return to shoot any remaining strings once the gun is functional, but the string the malfunction occurred on is always scored and is no longer available to be shot. For suspected safety problems, such as squibs, if upon examination of the gun there is no safety problem, then a reshoot is required. However, if there is a safety problem, no reshoot.
Note that this doesn’t cover failing to react to the start signal, which isn’t uncommon, especially on a loud range or if the competitor is double hearing protected. If that is the case, the RO must ascertain why the competitor didn’t react, and take steps to ensure they know when the timer has started.