Need help with my kwa sr7

[Darylhall]

So I was playing Sunday and tore up a piston. A friend of mine put his stock one in for me. Before it broke it was amazing 400 fps at around 30 a second. Now on semi auto it holds at around 400 but full auto velocity drops way off. Any suggestions on what's wrong. And any good reviews on any pistons and motors would help. Thank you guys.

[vulrath]

Sounds like a compression problem. Did your friend use his piston head or your old one?

[Black Hand Tattoo]

you shouldnt be getting 400 fps with a stock sr 7, they normally chrono between 330-360,( and thats with .20s) and the rpm is around 20 to 22, with 9.6 nimh , i had the same problem with the drop on auto, and i fixed it with a hop up change, those 2g buckings really suck IMO, i would just change the bucking and clean your barrel good before i would split open the gearbox again......

[Darylhall]

Guys at cartcon fixed me up. New spring,piston. Now chronos at 415 and .29 a second