Actually, we found after 40 years of building PPC guns, that we could get by with a lighter mainspring when the hammer had been bobbed or lightened. Seems we get more "snap" from from the lighter hammer. Hammer speed seems to be the key, and of course a lighter hammer doesn't need as much mainspring. Some of the mainsprings were so light on some of my PPC guns, you'd think they'd never work. Yet, I never had a failure to fire. All of my hammers are bobbed and extremely light.