Weaker than standard hammerspring designed to work with the FX Impact 720 & 750 power plenum.

A number of customers have asked us to source weaker than original hammersprings (for use when tuning).

We have 4 different strengths each slightly different strengths. S1 being the weakest and S4 the post powerful.

PLEASE NOTE: These will reduce power compared to the stock spring, but are for tuning and setting rifle up at a sweet spot rather than max power. In this case we generally find better performance running a weaker spring at higher load, rather than running the more powerful factory spring at reduced tension loads.

Sold individually