How much shooting have you done, and how high is your rate of fire. Piston bodies are generally considered the "consumable" part of the mechbox. High rate of fire tends to consume it a lot faster.
Edit: Just saw your gearset is a high speed set. You need a stronger piston in order to take the high speed setup. This would work fine..
http://www.airsoftparts.ca/store2/in...oducts_id=1173