Base on S&T M40A3.
We installed PDI FAT dia spring , piston & SP guide to their M40A3.
The piston is HARD piston ,so more durable & easy handling.
The SP guide is RAVEN SPRING GUIDE.
Please select your likely power from below.
All data are with 0.2g BB
* Please note these springs are too power,so take care of your gun condition.
Also RAVEN 455mm Inner Barrel is installed.
Inner Dia. is 6.01+,it's a tight bore.
The material is Carbon Steel,black oxide coating.
* We use S&T package so there is no PDI name