I'm not sure how much airguns are meant to rely on spin stabilisation, but since the twist rate is similar to powder burners, it could well play a big part. Too much spin and the drag from the skirt is fighting the gyroscopic forces, particularly at long range. The equations indicate the length of projectile is a factor.
Many people have commented on how their results have been affected by wind at distance. Shooting the heavier caliber, since they are slower, I have seen certain pellets suddenly carried off by the wind beyond 40 yards or so.
I hypothesise a new theory: As the pellet travels further, the spin rate slows too and like a spinning top, it gets to the point where it starts to wobble and lose stability. How quickly it slows depends on the initial twist rate, velocity and BC. How quickly it destabilizes depends on how quickly it slows and the pellet length. Possibly other factors too.
Some day, experimentation with high speed film cameras in controlled conditions may provide more insight.