well it seems that the spring was the issue.

I used a stock CA spring and the gun fired without issues. It seems that the hurricane spring was causing the piston to jam.

Well the Hurricane was an M120 which is MUCH tougher. A stock CA spring is probably giving you almost 100 FPS less. I'm sure if you had a larger battery you could pull that stronger spring. The larger cells (even if they're lower voltage) have larger discharge rate. The bearing spring guide and piston head also make it more difficult.

or just recommend the guy to get rid of his crap Chinese parts and get AM parts that can handle the bloody thing:)

cheers all thanks again for the help!