when "cocked and locked", for instance. Care should be taken when handling firearms of uncertain origin, and only a competent gunsmith should be relied upon to verify the safety mechanisms of surplus guns are intact. Because the sear must overcome the additional spring pressure of the firing pin block, an inherent feature of the CZ 52 is its unusually heavy trigger pull, often in the range. The hammer is of the rebounding type, meaning that it does not contact the firing pin while in its uncocked position, and cannot do so unless the trigger is pulled, another safety feature. Using the decocker relies on the integrity of the firing pin block; if the firing pin block is worn, an unintentional discharge can result when the decocker is engaged. Because of this, the decocker is considered to be unreliable and its usage is not recommended. After a full magazine is inserted, the slide is fully retracted and released. This action cocks the hammer, strips a cartridge from the magazine, and chambers it. Rotating the three-position safety lever fully downward, exposing a red warning dot between the receiver and the hammer pivot pin, renders the pistol ready to fire. Rotating the lever upward to its center position covers the red dot and engages the sear block (allowing "cocked and locked" carry). Finally, rotating the safety lever fully upward decocks the hammer by releasing the sear and intercepting the hammer's forward movement. This position allows safe carry of the pistol with a round in the chamber. The hammer must then be cocked manually and the safety disengaged before a round can be fired. As the trigger is pulled in this state, the trigger bar rotates the sear, a lug on the sear disengages the firing pin safety located directly above it, and the opposite side of the sear releases the hammer. The hammer then impacts the firing pin, the firing pin impacts the primer of the cartridge, and the shot is fired. The CZ 52 utilizes a fairly uncommon variety of the short recoil operating system in which two vertical rollers are used to lock the barrel and slide together, via a cam block. This is similar to the system used in the German MG 42 general-purpose machine gun. This arrangement results in a strong lockup which, conventional wisdom holds, allows the loading of higher pressure ammunition (such as ammunition intended for use