During spin-up the lateral force on the projectile increases slowly until it reaches maximum. When it's released, this load disappears almost instantaneously a

During spin-up the lateral force on the projectile increases slowly until it reaches maximum. When it's released, this load disappears almost instantaneously and the object is effectively in free-fall ... effectively 0g. Then it hits the atmosphere and is subjected to significant drag, but that onset is reasonably slow (by some metric) compared with the release mentioned above, but it's along a different axis. What's more, the projectile has spin along its long axis ... I don't know how that's imparted. Yeah, there are some huge forces that change rapidly in lots of directions.