Air down the barrel is usually the cupseal. Take the part below the barrel off, take out that spring and the thing attached to it is the cupseal. Check that and see if its got a good lip and seal on it. If you ever have problems putting the hammer and bolt back in, push that thing called a sear release( On the grip frame) and it'l let the hammer slide in. If it gets stuck coming out, make sure all the O-rings on the bolt are good. If ones damaged or broke it can jam the gun up.
Piranha Evo,Ext and Gsx.