Hammer Power Spring This is the next power up from AF stock hammer spring. For shooters who feel they need a harder hitting hammer. Power Spring is pictured on top. Below is an AF stock hammer Spring OD (in) 0.975 ID (in) 0.831 Free Length (in) 4.000 Rate (lbs/in) 6.200 Sugg. Max Defl. (in) 3.000 Sugg. Max Load (lbs) 18.000 Solid Length (in) 0.760 Wire Dia. (in) 0.072 Total Coils 10.500 Material Music Wire Ends Closed Ground Finish None