The ULTIMATE® Upgrade Series doubled progressive springs make sure the torque of the motor is used to its full extent giving a higher rate of fire. This spring is chromium plated which minimizes the friction on the piston. Chromium plating does not wear off leaving unwanted debris in the gearbox.

Most be used with appropriate ULTIMATE® upgraded internal components to secure the best performance and durability.

The ULTIMATE® springs are named M100, M110 etc. according to their expected tension in meters per second – measured when using a 0.20gr BB and a 300mm long barrel. In turn, a M110 spring would give 110 m/s. To convert to feet per second (fps) simply multiply by 3,28, e.g.: ref. 16671 – M120 – 120ms/394fps.