Indeed the decocker raises the firing pin disengage and what stops the hammer from falling appears to be an intercept notch. If this is worn, the firing pin plunger in the slide may or may not stop the firing pin from striking the primer when decocking. Other guns, such as the Makarov have a cam from the safety move directly in the hammer's way. We have yet to rip apart the pistol and determine what causes this. In the mean time please be careful about decocking the pistol with a round in the chamber and do not rely on this mechanism to safely decock the CZ-52!