A steel spring with an unequal stroke designed for power tuning. It provides a muzzle velocity between 380 - 410 FPS (depending on the internal gearbox parts used). The fronts of the spring have been ground, which translates into its better operation.
![[SHS-08-001536] M120 Main Spring](http://forairsoft.com/cdn/shop/files/553c5be4eb18720a87e0cecb98cf65ae1ce20abc_1152195335_1.webp?v=1780657181&width=1445)
![[SHS-08-001536] M120 Main Spring](http://forairsoft.com/cdn/shop/files/07a8ad3a99a21e342d54d035955953c4cfaec4d5_1152195335_2.webp?v=1780657182&width=1445)