pbfree wrote ...

Yes, the cap back should be regulated always. Optics will not overcame change in cap voltage.

Optics is open loop because it in no way is reactive. Unless by some form of magic, when a projectile enters a certain stage too slow the optics cannot speed up the projectile anyway hence calibration does propagate to remaining stages. You must keep track of projectile speed at each stage, compare the difference against a look-up table and then compensate. Compensation of course would be to increase the delay between projectile optical detection coil firing proportional to decreased projection entry velocity. Compensation would not included a decrease in coil firing delay after detecting an unexpected increase in projectile entry velocity because this would mean the coils simply were not calibrated in the first place.