These 1911 parts meet or exceed original factory specifications. If you're building a gun, or wish to bring your 1911 back to true mil-spec, these parts will provide exceptional service. May require fitting to specific gun.
In general, heavy loads need heavy springs and lighter loads need lighter springs. There is no hard and fast rule as to how much "Spring" a pistol needs. Too light a spring and the pistol opens and closes early and hard, increasing the felt recoil and battering the frame. Too heavy a spring and the slide is hard to open and may not cycle completely, jamming the pistol.
Shooters who are using +P ammunition or self defense ammunition will likely need heavier recoil springs. Shooters who are using target ammunition may be able to use lighter recoil springs.