remains the main assault rifle of the Slovak army, the Slovak army has also been eyeing CZ-805 as a possible replacement to the aging vz. 58 rifles. Design details Operating mechanism The vz. 58 is a selective fire gas-operated weapon that bleeds expanding combustion gases generated in the barrel from the ignited cartridge through a port drilled in the barrel, from the chamber, opening into a hollow cylinder located above the barrel that contains a short-stroke piston. The vz. 58 does not have a gas regulator and the full force of the gas pressure is exerted on the piston head, propelling it backwards in a single impulsive blow. The piston is driven back only when a shoulder on the piston rod butts against the seating and no further movement is possible. There is a light return spring held between the piston shoulder and the seating which returns the piston to its forward position. The gas cylinder is vented after the piston has traveled back and the remaining gases are exhausted into the atmosphere on the underside of the cylinder via two ports. The entire piston rod is chromium-plated to prevent fouling. The locking system features a locking piece hinged from the bolt and housed in the bolt carrier that contains two locking lugs which descend into and engage locking shoulders in the receiver's internal guide rails. The weapon is unlocked by the short tappet-like stroke of the piston rod as it strikes the bolt carrier and drives it rearwards. After of unrestricted travel, a wedge-like surface on the bolt carrier moves under the hinged breech locking piece and lifts it up and out of engagement with the locking recesses in the steel body. The hinged breech locking piece swings up and this movement provides the leverage required for primary extraction. The breech block is then carried rearwards extracting the empty cartridge casing from the chamber. A fixed ejector passes through a groove cut in the underside of the bolt and the case is flung upwards clear of the gun. Features The spring-loaded extractor and firing pin are both housed inside the bolt, while the fixed ejector is slotted inside the receiver. The extractor retains the firing pin and is powered by its own plunger and spring. The weapon does not have a conventional rotating hammer but a linear hammer instead. The hammer is a steel cylinder hollowed from one end