Set of 3 custom hammer springs designed for use with the SSB (Solid-State Bolt) to tune the gas efficiency and hammer strength in a bolt-action or underlever KC-02, but can also be used with semi-auto guns to adjust hammer strength.
These springs are much shorter and stiffer than the standard hammer spring as they are designed to provide the "floating hammer" function necessary to achieve bolt-action operation. The different lengths have almost no effect on the FPS energy output of the gun, but will adjust the gas consumption used for each shot.
Which spring you need will vary depending on the other details of your build - such as barrel length, friction in the trigger mech, gas type being used. It's best to test your gun with all 3 and choose the one which gives the best results.
Most SSB guns will see the best efficiency and consistency with the -2 spring, though if you also want to use the gun with a semi-auto bolt, you may need to use the -1 spring as the blowback needs more gas than an SSB uses.
If you intend to only use your gun in normal semi-auto mode, then the 0 or -1 springs are probably best for you.
These 3 springs are included with the SSB as standard, and most of the underlevers will also ship with them from now on.