The Vz. 58 is a 7.62mm Rifle designed and manufactured in Czechoslovakia and accepted into service in the late 1950s as the 7,62 mm samopal vzor 58 ("7.62mm submachine gun model 1958"), replacing the vz. 52 self-loading rifle and the 7.62x25mm Tokarev vz. 24 and vz. 26 submachine guns. The vz. 58 externally resembles the Soviet AK-47 but is internally a completely different design based on a short-stroke gas piston.
Development of the weapon began in 1956; leading the project was chief engineer Jirí Cermák assigned to the Konstrukta Brno facility in the city of Brno. The prototype, known as the "Košte" ("broom"), was designed to chamber the intermediate Soviet 7.62x39mm M43 cartridge, rather than the Czech 7.62x45mm vz. 52 round, used in both the earlier vz. 52 rifle and the vz. 52 light machine gun. The assault rifle entered service in 1958 and over a period of 25 years (until 1984), over 920,000 weapons had been produced, fielded by the armed forces of the Czechoslovakia, Cuba and several other Asian and African nations.
The vz. 58 was produced in three main variants: the standard vz. 58 P (Pechotní or "infantry") model with a fixed buttstock made of a synthetic material (wood impregnated plastic, older versions used a wooden stock), the vz. 58 V (Výsadkový—"airborne"), featuring a side-folding metal shoulder stock, folded to the right side, and the vz. 58 Pi (Pechotní s infracerveným zamerovacem—"infantry with infrared sight"), which is similar to the vz. 58 P but includes a receiver-mounted dovetail bracket (installed on the left side of the receiver) used to attach an NSP2 night sight; it also has a detachable folding bipod and an enlarged conical flash suppressor.
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, 215 mm (8.5 in) 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 19 mm (0.7 in) 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 16 mm (0.6 in) 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 falling breech lock 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 22 mm (0.9 in) of unrestricted travel, an wedge-like surface on the bolt carrier moves under the breech locking piece and lifts it up and out of engagement with the locking recesses in the steel body. The 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.