Some Airwolfs did exhibit a change in POI when the reservoir pressure dropped below 150 bar, even though according to the chrono the MV hadn't changed. It could be something to do with the pressure pulse puffing out the pellet skirts and changing the BC, which would not show up at the chrono. I don't believe that Daystate ever bottomed out the true reason for this phenomenon. It was one reason why the firm limited their claim as to how many shots per fill you could achieve.
I think the solution is to keep the botle above 150 bar.