no idea, the guy who sold me this, told me he got mark(the gun doc) to install a M120 spring..But even the stock spring would shoot 380fps according to youtube videos, so its changed?
I don't really believe him after I shot it into a chrono at the field a few days after(paintball chrono should be the same as airsoft one eh?)
I was okay with lower spring just because of I do plan on playing indoor games, and that one has a rule of 330 max fps..so low.
I don't want to open the gearbox since I don't know anything about it. And it's a CA P90 so changing the spring would require opening the gearbox. (of course someone could scam me cause I don't know the internals)