Normally the spring is not needed. I have seen a few guns that the hammer nose could catch on the frame as the hammer went forward if the hammer nose happened to be in the "up" position. That is why on some frames you will see a notch in the top of the frame to deflect the hammer nose back down. The spring will hold it down all the time, until it gets to the hammer nose bushing, then it can pivot up to go through. If yours can't contact the frame as it goes forward, then it doesn't need a spring. If it catches on the frame, it can break off.