[e-luder]

The only one way see this happening is if the square piece that locks on the firing pin doesnt move up or down when the hammer is cocked. The function of that piece is to jam the firing pin so that the spring your are mentioning doeant pull the firing to the rear when the hammer is cocked. This is done via the little notch on the firing pin that the square piece fits into.

There is also a tiny apring that activatea that square piece. you can see it when you pull the hammer housing out. make sure you seet it properly. sometimes it gets hammes behind the hammer.