GMT M140 Spring

This is a M140 spring made by GMT. This is a dual stage spring, which means the coils get farther and close together in different parts of the spring. This is the way all aftermarket springs are while stock springs are constant rate. It changes how much force the spring applies at different points in the stroke. This spring is very powerful and should only be installed by an seasoned airsmith who knows how to build a gun that can handle this spring.

Features:
- .063" (1.6mm) wire diameter
- Best for DMR and sniper rifles

UASR rating: 4.94DR
Spring rate (6kg test): 981N/m
Spring length: 174mm
More information on UASR ratings here and here.