Description: ALG Defense Purple Hammer Spring, can be installed onto your ACT hammer to provide an approximate pull weight of 4.5 lbs. This spring is perfect for those who are using their rifles for recreational purposes and target shooting. When shooting the ACT with the purple hammer spring and firing military grade ammo or ammo with harder primers, light strikes may occur. If there are light strikes, it is recommended the user switch to the tan hammer spring. The Tan Hammer Spring will give you a pull weight of 6.0 lbs., which meets the minimum required pull weight of 5.5 lbs. in the M4 Carbine specifications.