Nighthawk Custom, Gov't Recoil Spring #20

On most Government (5") size guns, we suggest you use a 17# to 18.5# spring for standard factory ammunition (2,000 rounds). If you plan on having an extended shooting session using hot or +P ammo, then opt for the 20# spring. It works well on ammunition like Winchester Lawman. If you want to shoot some reduced loads, then drop back to a 15#. Commander (4.25") size guns work best with a 18# Commander spring (1,500 rounds). For a steady diet of hotter ammo, put in a 22# Commander spring. Officer (3.6") size guns use the 24# spring. Since you change them every 500 rounds, that particular weight should suffice. It is also a good idea to change your mainspring (hammer spring) and firing pin spring every 5,000 rounds on all sizes.