Now treated with Plate+ Penetrating Moly Formulation for longer duty cycle life  Our 1911 and 2011 recoil springs are manufactured from Chrome Silicon. Chromium-silicon alloy is noted for it's hardness and superior performance at extremely high stresses. Because of it's heat resistance and hardness, the alloy can be used in valve springs and automatic transmissions at temperatures over 275F. Chrome-silicon was originally developed for recoil springs in anti-aircraft guns where high resistance to shock loads and long life is needed. The endurance limit of Chrome-silicon either before or after shot peening equals that of carbon steel in the same condition. At a given stress value, it can be used at a temperature 100 degrees Farenheight higher than Chromium-vanadium and higher hardness without breaking. This alloy provides excellent service for applications in the 5,000 to 50,000 cycle ranges. Available in a sensible range of popular weights, professional shooters and manufacturers who have tested our springs attest to the fact that our springs meet and maintain spec performance better than any other recoil spring on the market today. 1911 PERFORMANCE TIP Many of our professional shooters have achieved impressive results by combining our Chrome Silicon Recoil Springs lighter than "normal" weights with the Sprinco Recoil Management System. The net result is reduced muzzle dip when the slide returns to battery, hence, improved rapid-fire control! We recommend running a 2-6 pound lighter load spring than the "factory" recoil spring. Please contact Technical Support for suggestions with your particular gun and loads.