Spring Prometheus MS110 AEG Aqua

The Prometheus MS110 AEG Aqua features what Prometheus itself calls a non-linear spring — in practice a progressive spring. This means the spring is constructed from coils with varying spacing. Coils positioned closely together provide less resistance; the more widely spaced coils are stiffer. Because the resistance increases gradually rather than building up immediately, the piston teeth and gearbox are subjected to considerably less stress with each cycle.

How this works in practice: at the beginning of compression, spring pressure is low. As the more tightly wound coils come into contact and the stiffer coils take over, pressure increases. In the final part of the stroke, pressure builds up as it would with a linear spring over the full length — but concentrated in that closing section.

For the lifespan of the internal components of an airsoft replica, this is a clear advantage. Moreover, a powerful motor with a progressive spring can build momentum better toward the heaviest phase of compression, which benefits the rate of fire. A common choice for shooters who want to limit gearbox wear without sacrificing speed.