[Shell Shock]

hmm.. sounds like a problem i faced with my old mp5. if so, my solution is simple and highly effective. all you need is some Teflon tape (used in plumbing and air systems.. see where im going with this?)

1- disassemble AEG until you have full access to the following: hopup, gearbox and inner barrel

2- remove the inner barrel from the hop up and wrap a layer or two of teflon tape around where the inner barrel and the hop up meets (not where the "nub" goes through though)

3- open your mechbox and put one or two wraps of Teflon tape around the piston head.

you must make sure you do this very neatly, or in a month you will have to clear your inner barrel of Teflon tape and start again.