Intermediate ballistics are from the moment your projectile exits your muzzle up to the point where it is no longer affected by the gases exiting your muzzle, that will lead into exterior ballistics.
Gases will still affect your projectile and its velocity a very small distance once it has left the muzzle, creating a Mach cone.
Intermediate ballistics are the reason you would use a flash hider to minimize flaming gases (your flash) or a muzzle brake to tame the recoil.
Crown will also affect Intermediate ballistics as to how your gasses are pushed behind the exiting projectile. If you go from a straight barrel to a muzzle device, that will play with your gasses exiting your muzzle so it will change your intermediate ballistics.
Not necessarily bad or good, just saying keep that in mind.