Evike.com Irregular Pitch Airsoft AEG Tune-up Spring (Power: M170 560~580 FPS)

"I am not sure if it doesn't fit or if I am not trying hard enough. Either way I cannot fit it in my CYMA Ver. 3 gearbox.

"Chrono at 421 fps the other day with this spring, it shot too hard to be used. Guess perfecting my airseal was a bad idea since this spring is harder than is advertised.

"I purchase M 130 for my Kwa M4 it was too long it would not fully cycle almost screwed up my gearbox a no go for me thank you.Spring of good quality metal only good thing going for it.