MM S400 1.8 Spring

Not every S400 owner wants to stay down near the 200FPS mark, but jumping straight to a 300+FPS spring is overkill — or against field limits — for a lot of games. The MM S400 1.8 Spring is built for exactly that middle ground, landing at an average of 250FPS when installed in the S400 blaster, which is enough of a step up to feel meaningfully different without pushing into high-power territory.

This is a main spring swap, so it goes inside the blaster's priming mechanism rather than being a drop-in external part. Please be careful when changing the main springs on the S400 — this applies to any spring swap, but especially when working with or removing the 2.0 spring, where care during disassembly matters most. If you're not confident opening up the blaster, take it slowly or get guidance rather than rushing it.