Strange effect after lubing pellets on Hatsan Atp2

My Hatsan At P2 cal 22 shots RWS Hobby pellets in the Range 720-850-720 fps by a pressure from 200-150-90 bar.

Its accurate tilll 35 Meters with those Flathead Pellets if there are dry.

I make asome tests with different lubes ballistol...graphit etc.

With the ballistol lubed pellets i have a drop when i reach the 150bar to 440fps.

And its stabel from there down to 80 or 90 bar.

How can this be?

Have anyone in his Airgun this effect?

And its just with lubed pellets when the gun reaches the 150 bar mark it drops direct 400 fps

I dont shot lubed pellets becouse they dont shot well but the effekt is strage