History of the Sa vz. 58 design

In the years following World War II, Czechoslovakia continued to see a greater need for infantry rifles that could sustain a higher rate of fire than previously fielded service rifles. There was a growing need for an improved rifle that could combine select-fire and higher magazine capacity of the submachine gun with the longer range and energy of the self loading rifle. The concept of such a rifle emerged in Czechoslovakia in 1946, but development was not ordered until 1951.

In 1951, three independent engineering teams worked on the development of a select-fire rifle. One of these three teams included a young designer named Jiří Čermák. With the knowledge he had acquired from the designers of the Model 52 rifle, he designed the ČZ 515 prototype assault rifle for the 7.62x45 mm cartridge. This prototype possessed the following characteristics: shortened barrel of the Model 52 rifle, fired from the open bolt position (a requirement of the army because of the perceived danger of a self-ignited cartridge), a non-reciprocating charging/cocking handle, and a trigger mechanism with two individual triggers that enabled both single shot and full auto firing.

 

 

During testing it was found that the ČZ 515 did not meet the accuracy requirements demanded by the Czechoslovakian army. This lack of accuracy was attributed to the open bolt firing system. To address the issue, Mr. Čermák re-designed a second prototype rifle, the ČZ 522, to fire from the closed bolt position. In addition, the barrel of this new prototype was shortened to 350 mm and had the charging/cocking handle attached directly to the bolt carrier. In 1954, the ČZ 522 and two other prototypes (from competing engineering teams) were tested by both the Czech Army and the Red Army in the Soviet Union. During this testing it was found that all three rifles needed improvement, but the Soviets praised the ČZ 522 over the two competing designs.

The next major development was influenced by the political-military decision, made in 1955, to abandon the 7.62x45 mm cartridge for the Soviet 7.62 Model 43 cartridge (7.62x39 mm). Going forward, all prototype rifles were to be chambered in 7.62x39 mm. During this period, the Koucký brothers (original participants in the project) left development of military small arms and went into the civilian firearms business. Beginning in 1956, only two teams continued with the project. In addition, continued developments led to a greater demand of tactical-technical requirements which included the following:

  • weapon weight: max. 5.95 lbs without a magazine (originally 8,82 lbs with magazine)
  • weapon length: max. 33,4646 in
  • magazine capacity: 30 cartridges
  • number of magazines: 6
  • max. fail rate: 0.3%
  • durability of main parts: 15,000 shots
  • open sights up to 875 yds in 109 yds increments
  • shot dispersion at 109 yds in lying position with support – single shots: 3,94 in
  • shot dispersion at 109 yds in lying position with support – short bursts (3-5 shots): 8,27 in

Further requirements were brought forward and the new rifle had to possess the following: machined parts that were 100% interchangeable between same models, possess a smooth left side for easy carrying using a sling, possess a bolt hold-open after the last round had been fired (for increased firing readiness), design a gas piston that would be separate from the bolt carrier, and magazines made of light alloy to reduce the overall weight of the soldier's combat load.

During the next phase of design work, the idea was to replace the hammer with a striker system. This was expected to achieve a lower cyclic rate of fire which was later confirmed to be correct. Moreover, it was found that the added travel time of of the striker system reduced shot dispersion in full automatic fire.

Military testing

In the first quarter of 1956, the Soviets had finally given the Czech designers drawings and samples of 7.62x39 mm cartridges. Waiting for these drawings and samples delayed the development of the new prototype assault rifle. The first prototype to use this cartridge was the model Sa-56.

The weight of the Sa-56 was approximately 3.2 kg and had exceeded the weight limit mandated by the Czechoslovakian army. Even at this weight, the Sa-56 showed great promise and was considered a success when compared to the ČZ-522 prototype. After the internal development and improvement phase had concluded, 12 prototypes were ordered for military testing. These prototypes possessed an exact weight of 3 kg each. The additional weight reduction was achieved by making the magazine from aluminum alloy (the weight savings with the six magazines were 0.9 kg).

These 12 Sa-56 prototypes showed some faults during testing that was conducted in both Czechoslovakia and in the Soviet Union. One problem was attributed to the insufficient durability of the firing pin. The other issue proved to be an intermittent problem of self-ignition ("cook-offs") where a chambered cartridge would unexpectedly fire due to extreme heat. This was determined to occur at approximately 180 shots (the number of carried cartridges in a combat load). It was found that the cartridge chamber became excessively hot by the escaping gas in the receiver of the rear site area. While correcting these issues, it was realized that the maximum specified weight of 2.7 kg would be very difficult to achieve with a rifle using a milled receiver. Nevertheless, thanks to the weight savings of the aluminum alloy magazine, the total weight achieved was 3.10 kg. These findings were accepted by the army and the resulting weight of 2.9 kg for the weapon itself was approved. In comparison, the milled receiver AK-47 weighed approximately 1 kg more than the final version of the Sa-56. Even the stamped receiver AKM (modernized version of the AK-47) weighed more, at 3.15 kg, than the Czechoslovakian assault rifle.

Production

After trial production and further testing and evaluation in 1959, the weapon was finally approved for serial production which started at the end of 1959. From 1959 to 1984, when the production of the Sa vz. 58 was terminated, almost 920,000 pieces were made in total and the weapon was exported to many countries around the world. The vz. 58 is still the issued rifle of the Czech Republic, Slovakia, Cyprus, Angola, Ethiopia, Guinea, Libya, Mozambique, Somalia, Tanzania, India, Iraq, Cuba and Guatemala.

When serial production began, the weapon’s designer Mr. Jiří Čermák was 33 years old.

Sa vz. 58 carried by Czech Forces in Afghanistan

Technical specifications of Sa vz. 58 assault rifle:

  • Caliber: 7.62 x 39 mm
  • Muzzle velocity: 771 yds / s
  • Effective range
       against ground targets: up to 655 yds
       against grouped targets: up to 957 yds
       against air targets: up to 547 yds
  • Maximum range: 3,060 yds
  • Theoretical shooting speed: 800 shots/min.
  • Practical shooting speed
       firing single shots: 40 shots/min.
       firing short bursts: 120 shots/min.
       firing long bursts: 150 shots/min.
  • Maximum continuous fire: 270 shots
  • Weapon weight without the magazine and bayonet: 6.42 lbs
  • Weapon weight with full magazine and bayonet: 8.31 lbs
  • Weight of the empty magazine: 0.42 lbs
  • Weight of the full magazine with 30 cartridges: 1.50 lbs
  • Bayonet weight: 0.40 lbs
  • Weapon length with bayonet: 39.37 in
  • Weapon length without bayonet: 33.27 in
  • Weapon length without bayonet, but with the folded shoulder stock: 25.04 in
  • Barrel length: 15.35 in
  • Number of grooves in the barrel: 4
  • Rifling lead: 9.45 in
  • Weapon width: 2.32 in
  • Weapon height with magazine: 9.96 in
  • Trigger resistance: 37.26 N

The Sa vz. 58 assault rifle was a great answer of still independent Czechoslovak designers to the Soviet requirement of caliber unification among Warsaw Pact countries. The Sa vz. 58 with its strict parameters (2.9 kg weight and 845 mm length), developed almost fifty years ago, can still be found on active duty around the world.

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