HSA Main Spring Shim SetHSA-MSS
HSA Main Spring Shim
Fine tune the power of your AEG with this lightweight set of shims. Designed to fit inside the piston, they raise the FPS by pre compressing the main spring, increasing stiffness. They can be stacked in many combinations to product various different total thicknesses. They weigh very little, so do not increase the piston assembly weight significantly.
Warning: Make sure that the total thickness of the shims plus the compressed (solid) length of the spring is less than the travel of the piston.
Small shim ~ 1-4 fps
Medium shim ~ 8-12 fps
Large shim ~ 18-24 fps