This gun i have is pretty old. It was my grandpaps he used to shoot comp with it. I decided i was going to clean it up and join a league using it....but will not shoot. The only thing i can think of is the firing pin will not lock back in place. Does anyone know if there an adjustment on it or does it sound like a spring or something is broke inside. O will not dry fire bec pin isnt locking back. help me please.