Custom Tune Spring Kit, Colt Officers, .45ACP. 21# Reduced Power Hammer Spring, Extra Power Firing Pin Spring, 18 1/2# Reduced Power Recoil Spring, 24# Extra Power Recoil Spring. Pkg. Includes: Mainspring (Hammer Spring), Firing Pin Spring, Extra Power Recoil Spring and Reduced Power Recoil Spring. A properly tuned 1911 Auto is unquestionably the finest combat pistol in the world. The first step when tuning your pistol is replacing the stock springs with Wilson "Custom-Tune" Springs. These springs are produced from the finest high tensile spring steel, assuring a consistently smooth action, positive ignition, and proper timing. Once installed, your pistol will be "Custom-Tuned" for maximum reliability. Mainspring (Reduced Power) for reduced hammer tension, resulting in easier cycling and up to 25 percent reduced trigger pull. Firing Pin Spring (Extra Power) Increased firing pin tension for longer life, and enhanced safety should the pistol be dropped. Heavy-Duty Recoil Spring (Extra Power) Increases feeding reliability when shooting factory loads. Heavy-duty for longer life. Heavy-Duty Recoil Spring (Reduced Power) A lighter spring for light practice rounds. Heavy-duty for longer life.