Trap, our National Judge, will likely chime in here too.
At one time we toyed with the idea of setting an minimum angle of lever operation. Lone Gunman even had a nifty illustration. Quite frankly, that angle was such that there would have been NO advantage in having a short-stroked kit installed.
But the more we discussed it, the more it became clear that going down that road implied that short-strokes could get by as long as they met or exceeded an 'official' measurement.
Short-strokes and similar mods are disallowed, period.
So I guess the proper answer, as to how we measure whether a firearm is short-stroked, is to look you in the eye when we say we trust you to be honest and play by the rules.
RCJ