damaged HATSAN AT44 PA .25 from dry fire (no air)

That gun has the valve in the end of the tank, If you remove the tank you'll be able to see if the bent the valve. If you try to fill it and air come's out of the tank it very likely that the valve is bent. Your gun came with a replacement valve seat (the small white ring thing with the o ring on it). your gun may still have a good valve but the seat wont hold air. Just guessing because you dry fired you gun with no air in it, it must have a leak.. Id recommend you remove the end and roll the valve pin on something flat like a mirror to check to see if its bent. If you need a valve I may have one for you. PM me if needed