Nighthawk Custom Spring Kit Government 9mm. The springs of a 1911 pistol relax over time especially with hard use. Having the best quality springs for your 1911 is critical for reliable function whether on the range or in self-defense applications. The Nighthawk Custom spring kit includes the springs you will need to build or re-build your pistol. This spring kit is designed for a 9mm 1911 and includes two standard recoil springs an extra power recoil spring for +P loads a reduced power mainspring and an extra power firing pin spring. Specifications for Nighthawk Custom 1911 9mm Spring Kit: Manufacturer: Nighthawk Custom Fabric/Material: Steel Package Contents: Nighthawk Custom 1911 9mm Spring Kit Nighthawk Custom SP0399: Spring Kit Government 9mm