Spring M120 Airsoft Evolution [SLONG AIRSOFT]

I recently upgraded my build with the SLONG Airsoft M120 Spring, and I have to say – this spring punches way above its price point. It delivers reliable FPS, smooth compression, and zero signs of fatigue even after extended use.In my 6.03mm tightbore setup with a ported cylinder, I’m getting a rock-solid ~395-405 FPS with 0.20g BBs. The spring is made from high-quality steel with a clean finish – no burrs, no uneven coils. The progressive design makes compression feel smooth and manageable, even when pulling manually during installation. Fits like a glove in V2 and V3 gearboxes. I paired it with a reinforced piston and bearing spring guide – no issues, and the tension feels just right for long-term reliability without overstraining parts. The SLONG M120 is a premium spring without the premium price. Whether you’re building a DMR or want to push your rifle into the high-FPS category for outdoor play, this spring is 100% worth it.