H&K USP Hammer Spring 16lb. $12.97 16lb. extra power hammer spring for the H&K USP 9/40/45. Factory standard weight is 14lb. 30816 In stock H&K USP Hammer Spring 16lb. quantity Add to cart Categories: HK, Wolff Gun Springs Related products Enfield 1914 / 1917 Rifle Service Pak $24.97