Another Bullet Exit Question

[Longrange57]

We know that spent gases pass the bullet before exit. The dead air ahead of the gases and bullet will compress to some degree. In the air rifle world, the dead air ahead of the pellet and muzzle blast does weird things to a light skirted pellet. Air rifle stuff is different than burning powder and spent gases, however the air ahead of the projectile is the same. The air has a different density depending upon pressure/temp. compared to spent powders. Some claim there are videos that illustrate that a pellet is upset and often causes flyers as the pellet goes through what is considered dead air upon exit.
How would this compare to a bullet of a centerfire rifle moving through spent gases and then meeting air with a different density? How would jumping or jamming with more or less gases moving past affect this? Some claim a vacuum is created in front of the bullet, could this add to the issues of meeting the so-called dead air? This area where gases are ahead of the bullet have been referred to by some as an intermediate area--distinct from internal and external ballistics. In several conversations, it seems to be a consensus that it directly affects accuracy.
As atmospheric conditions change, and the density of the air goes up or down, could we compensate for these changes?
No trick questions, just wondering how some view what is taking place upon bullet exit, the gases in front of the bullet, and how that effects light or heavy bullets.