First of all, most spring kits are made by Wolff, regardless of brand. You can use a pocket screwdriver to install the rebound spring, I've done many trigger jobs, and have never owned a special tool for the rebound spring. Try a medium spring for both the hammer and the rebound slide. Adjust as needed, some guns work well with a light rebound spring, but they require some smoothing of the rebound slide, and inside the frame where the slide uh... slides. Make sure you give the rebound slide a goodly amount of oil on all sides, the potential for drag is pretty high there.