Your cocking the hammer and when you release it it just fires? Or is it actually locking back first?

First thing I would do is pull the lock. On the back side of it there are many little parts. Take some dish soap, and squirt some back there. Then with an old tooth brush gently scrub all the parts until they are clean. Then a drop of oil and put it back together. See if that helps. If not, take it to a gun smith.