Need new piston ring which one ?!
 

My kjw m4 V2 needs a new piston ring there are a few to choose from and I have no idea Wich ones are good or bad so some input would be awesome
Also do some piston rings loose performance and some gain a bit of performance ?
Any input wiuld be great Thx guys !

Quick way to rehabilitate a piston head o-ring, stretch it over your cylinder and heat it up. Let it cool and place back on to piston head. I have tried this method and it works

Has any one had any experience with the x- piston & ring from cradle airsoft ?

Are you asking about the piston or the ring because your OP is some what confusing.

If you're asking about the piston itself thats an entirely different field - the rubber ring you're also talking about are a dime a dozen and are for compression.

Heres a thread on pistons:
http://airsoftcanada.com/showthread.php?t=147664