Re-read my post. Nearly and almost because the timing cannot be exactly the same each time, but It can be very close, close enough that if the bullet is leaving at an inflection point, the differences will be industingushable. Your statement that no one, and no program can model vibration and deflection is comically ignorant and misdirected. Just because you can't do something , or don't understand something doesn't mean no one does. What you believe or feel about this subject has no bearing on the fact that this is a well explored field of study. A good model doesn't have predict every tiny nuance to be useful, just the effects that reliably explain the vast majority of the observed behavior. This is basic knowledge that all models are predicated on. You can think whatever you want is a waste of time, but that doesn't make it so.