CS/LS06 “Chang Feng” Submachine Gun

By N.R. Jenzen-Jones

The Chang Feng submachine gun (SMG)—known in its latest iteration as the “CS/LS06”—is in service with Chinese law enforcement and paramilitary personnel, as well as specialised units from other nations. The design is notable for its 50-round helical magazine and is often issued with a suppressor. Development of the Chang Feng SMG began in the mid-1990s by the Chongqing Changfeng Machine Company Ltd., based in the southwestern Chinese city of Chongqing.

The weapon was conceived by veteran designer Qing Shangsheng, under the auspices of the Changfeng Military Products Research Institute. In addition to leading the design team for the QSZ-92 pistol, Mr. Qing had previously worked on a number of other small arms projects, including the Type 64 7.62×17mm pistol, Type 67 7.62×17mm suppressed pistol, Type 80 7.62×25mm submachine gun, Type 56-2 self-loading rifle, both 7.62 and 5.45 light machine guns (“squad automatic weapons”), and a variety of sporting pistols, a signal pistol and even a derringer. Prior to working on the CF05, he had already secured a patent for a high-capacity quad-stack, double-feed magazine for the Type 56-2.

Prototypes

According to a 2006 interview with the designer, he initially developed the concept in secrecy between 1993 and 1994 and did not share it with the factory manager until 1996. Four main series of prototypes were then developed. The first prototype used the weapon’s helical magazine to form part of the buttstock, fitted with a removable rubber butt pad. Versions of Prototype I were developed with different burst functions: Prototype I-1 had a two-round burst mechanism, and Prototype I-2 had a three-round burst mechanism. The second prototype’s magazine moved so that it sat above the barrel and introduced the closed-bolt, blow-back operation.

Prototype II was fitted with a telescoping stock. Both Prototypes I and II were chambered for 5.8×21mm.

It was determined that export sales were to be a priority for this weapon, and the weapons were updated to chamber the internationally popular 9×19mm cartridge. At this point, the program adopted the designation “QC-9” for the guns. As well as the new chambering, Prototype III saw experimentation with under-folding buttstock designs. Prototypes III-1 and III-2 have slightly different folding stock configurations. Prototype III-2 also introduced an optics mounting capability.

Prototypes I, II and III were all able to feed from a secondary feed device—a detachable box magazine housed in the pistol grip of the gun. These were QSZ-92 pistol magazines, which are produced in both 5.8×21mm and 9×19mm versions. A separate magazine release, located on the pistol grip, is visible in the first three prototype series. In the first prototype, it was possible to inadvertently introduce a feeding issue with both magazines fully seated. In Prototypes II and III, the box magazine could not be fully seated until all rounds were fired from the helical magazine, tripping a switch.

By Prototype IV, the design had returned to using a telescoping buttstock, and the alternate box magazine feed system was removed. A magazine release button is still seen on the pistol grip of all prototype weapons. In Prototypes II and III, the forward and rear pistol grips are connected via a bridging structure. Prototype IV-1 also has this “bridged” configuration; however, by Prototype IV-2, the furniture design is essentially finalised and is close to the production gun. The prototypes had a cleaning kit stored in the front pistol grip, which was also dropped from production guns. By the last prototypes, the translucent brown helical magazines appear to have been introduced, and translucent white magazines followed in early production guns.

A number of further changes were made as the QC-9 progressed through development. The weapon underwent trials in 2004, and issues with extractor strength, feeding issues, trigger issues, and the fire selector were resolved. The weapon was finally approved for serial production in May 2005. The production version of the weapon, now designated the CF05, was publicly showcased at the first annual China International Exhibition on Police Equipment and Anti-Terrorism Technology and Equipment (CIPATE) on May 10, 2005.

Export Variant

In 2006, the export variant of the weapon was approved, and the designation CS/LS06 was applied. Export versions of the weapon have occasionally been marketed as the Type 06, but CS/LS06 remains the most common name. “CS” likely stands for “China South,” as in “China South Industries Group,” which included Changfeng amongst its subsidiaries. This designation is seen on the title page of an English-language SMG manual from the mid-2000s (China South Industries Corporation’s “Operation & Maintenance Manual of 9mm Light Submachine Gun Type CS/LS06,” state-owned document #236), which was intended for the export version of the gun. It has been suggested by several observers that “CS06” is the designation for the firearm, whilst “LS06” is the designation for the suppressor. Not only is there no evidence to support this claim, “CS/LS” designations are applied to other export submachine guns without suppressors. The Changfeng Machine Company merged with Jian She several years ago, and so the “CF05” designation is unlikely to be used again.

The Chang Feng design is a hammer-fired, blow-back operated submachine gun chambered for 9×19mm, firing from a closed bolt and feeding from a 50-round helical magazine. The design uses a telescoped bolt which wraps around the barrel when in battery. At the end of its rearward travel, the bolt is stopped against the rear of the barrel assembly, rather than the receiver. The polymer receiver features a collapsible stock, and the barrel is threaded to accept a suppressor, which is typically supplied with the gun.

CS/LS06 Features

The CS/LS06 features a combined fire selector/safety, which allows for safe (B), semiautomatic (D) and automatic (L) modes to be selected. The selector can be removed like a “key” to the gun, locking it in the safe position. A three-position aperture sight is marked for 50m (“5”), 100m (“10”) and 150m (“15”) engagement ranges. The stock is extended from the collapsed position simply by pulling it rearward. It is collapsed by pressing in the buttstock latch on the left-hand side of the weapon. Detailed disassembly is quite complex, but a basic field strip can be conducted relatively quickly without tools.

The most notable feature of this weapon is its 50-round helical magazine. Helical magazines, often confused with drum magazines, use a staggered-helix design, which allows for a substantial increase in carrying capacity in a relatively compact form-factor. This results in a cylindrical magazine, which is often (as in this case) mounted above the weapon’s receiver, rather than below it.

Whilst helical magazines have been repeatedly tested in western countries (one early example of an internal helical magazine can be seen in the Evans Repeating Rifle, patented in the late 1860s, for example), they have typically found more favour in China, Russia and their client states. Perhaps the magazines of this type, with which most western readers will be familiar, are those used with the American Calico series of firearms. In fact, Qing expressly stated that the CF05 helical magazine design was influenced by a research trip a colleague took to the United States, where this person observed the Calico designs. Nonetheless, the construction of the magazine is closer to the Russian PP-19 Bizon submachine gun type.

Their inherently complex design makes helical magazines more prone to failure. The Chang Feng SMG manual gives a “failure rate” for the weapon of “equal to or less than 3 ‰,”  or three failures in every 1,000 rounds fired (1 in 334, or thereabouts). This failure rate would be considered unacceptably high by modern western standards, even under the assumption that this probably refers to all stoppages rather than just parts “failures.”

Reloading the magazine is a much more complex operation than that for conventional detachable box magazines. According to the gun manual:

5.2 Cartridge loading: Load required cartridge from loading port of cylinder (as shown in fig. 26, never miss loading), then apply spring force clockwise (as shown in fig. 27). Each turn of cylinder could contain 8 rounds and 50 rounds at maximum. Turns of spring force required is decided according to loading rounds. Turns of applying spring force equals to (X+1;n—rounds of loading cartridge [sic] …

That wording will likely be opaque to most readers, but thankfully the manual also includes a table which makes the process comparatively straightforward. Paraphrased, it indicates:

Table 1

Whilst the export weapons have almost exclusively been seen with opaque black polymer magazines, the manual notes “This gun is equipped with black opaque cylinder; if cartridge indication is required, brown semi-transparent cylinder could be equipped.” The weapon is typically offered for export with Chinese-made accessories, including a laser/light module (LLM; the most common appears to be the LLR-2), optical day sight, grenade launcher and suppressor.

The latest model of the gun features HK-style red and white pictographic safety/selector markings, new furniture textures, a forward-canted front pistol grip and trigger guard, a modified stock design and the model name moulded into the plastic on the left-hand side of the weapon.

The suppressor attaches via a left-hand metric thread on the barrel, located behind the muzzle device. A retaining/indexing pin is located below the muzzle. The SMG manual recommends disassembly and servicing of the suppressor after 150 rounds have been fired. Some limited suppressor testing was undertaken by Dr. Philip H. Dater and Dan Shea, the results of which were published in the Small Arms Defense Journal, “Chinese CS06 LSMG and LS06 Suppressor,” Vol. 3, No. 4.

In Service

The Chang Feng submachine gun has been documented in service with Chinese police and paramilitary forces. It is used by the elite No. 1 Detachment of the Beijing Special Weapons and Tactics Unit, known as the Blue Sword Commando Unit. Other police units around the country have also used the weapon, and it has been documented in a number of high-profile police actions, including protection of the Beijing Olympics and a hostage rescue action in Changchun, the capital of China’s northeast Jilin Province.

The weapon is also issued to components of the People’s Armed Police, including 3rd Group, 13th Detachment of the Beijing General Corps, known as the Snow Leopard Commando Unit. Snow Leopard personnel were observed carrying the weapon during training prior to the Beijing Olympics and in the Sino-Russian “Peace-Mission 2007” joint military exercise. In recent years, Chinese security forces are believed to be moving away from the Chang Feng design and toward new designs which are supposedly capable of firing a broad range of 9×19mm ammunition, from less-lethal to +P+ loads. Nonetheless, those that remain in arsenals are likely to continue to be seen.

A number of export sales have also taken place, with confirmed transfers to Myanmar (Burma), Venezuela and Uganda. In Venezuela, the weapon is used in a close personal protection role by the 509 Special Forces Battalion of the Army, Presidential Honor Guard personnel and members of the Special Unit for Security and Protection of State Personalities (UESPPE).

TECHNICAL SPECIFICATIONS

Calibre: 9×19mm

Overall Length (buttstock collapsed): 412mm (w/out suppressor); 631mm (w/suppressor)

Overall Length (buttstock extended): 595mm (w/out suppressor); 814mm (w/suppressor)

Barrel Length: 232mm

Weight: 2.2kg (empty w/magazine); 2.9kg (loaded with 50-round magazine)

Sight Radius: 285mm

Rate of Fire: 800 rds/min

Feed Device: 50-round detachable helical magazine

V0: 360 m/s

SOURCES

 ARES CONMAT Database.

China South Industries Corporation, “Operation & Maintenance Manual of 9mm Light Submachine Gun Type CS/LS06,” State-owned document #236. [No date.]

FirearmsWorld. “CS/LS06” 2012. firearmsworld.net/china/smg/cf05/lwsmg.htm.

NORINCO, Small Arms. Sales catalogue. 2012.

Pérez, Pedro, “Chinese ‘Chang Feng’ Submachine Gun in Venezuela.” The Hoplite Magazine. August 19, 2019. armamentresearch.com/chinese-chang-feng-submachine-gun-in-venezuela.

Special thanks to Ellie Chang, Pedro Pérez, Maxim Popenker and Timothy G. Yan.

This article is reproduced courtesy of Armament Research Services (ARES). See www.armamentresearch.com for further original content.

The Red Army leaders were quite confident that they could easily overcome any resistance from the Finnish army, which they outnumbered more than three to one.  The Soviets also had substantially more artillery, tanks and aircraft.  What the Soviets didn’t count on was the heavily forested terrain and narrow unpaved roads, which provided a perfect environment for the Finn’s guerilla tactics.  Armed with submachine guns, the Finnish Army put up a fierce resistance by continually ambushing the Soviet forces and then melting into the forest.  The Soviets eventually prevailed in March of 1940 and hostilities ended.  But the Soviets suffered far heavier losses than anticipated and settled for far less than a total victory, but lessons were learned.

A U.S. Army officer with two PPSh type submachine guns captured from Chinese soldiers. (NARA)

Along with the tactics of the Finns, one of the weapons instrumental in keeping the invading Soviet Army at bay was the 9mm Suomi KP-31 (konepistooli) submachine gun.  The KP-31’s fast cyclic rate, and large capacity drum magazine, was responsible for inflicting many casualties on the Soviets.  The Soviets were obviously impressed as they soon began fielding their own submachine guns and drum magazines that were suspiciously similar to the Finn’s.

The Soviets had taken note of the German’s limited use of a rapid firing pistol caliber MP18 submachine gun fielded near the end of World War I, and began development of a domestic design as early as 1926.  However, weapon development had a low priority in the post First War years.

A large cache of weapons captured from the Chinese by the Cavalry Regiment, Capital Division, Republic of Korea Army, 22 October 1951. Note the large number of PPSh 41 type weapons, all with drum magazines. At the end of the row are several PPS-43 type submachine guns. (NARA)

The 7.62x25mm PPD Submachine Gun
Soviet designer Vasiliy Degtyarev had introduced several promising weapon designs by 1931.  Development continued until 1934 when his 7.62x25mm M1934 Degtyarev submachine gun, the PPD (Pistolet-Pulemyot Degtyarev), was adopted for arming senior officers, but production of the PPD was very limited.  Degtyarev continued his work and introduced an improved model, the M1934/38 PPD that used a 25-round box or 73-round drum magazine.  The drum magazine had an extension on it to fit up through the stock.  However, in 1939 a decision was made by the People’s Commissariat for Defense to stop production and withdraw existing submachine guns from service.  They determined the submachine gun would have a limited range, waste ammunition and had little military value – ironically an opinion shared by the U.S. and Great Britain at the time.  The Soviet leaders changed their minds during the disastrous “Winter War” with Finland.  On 6 January 1940 the Commissariat for Defense ordered that large numbers of submachine guns be issued to the army.

Vasiliy Degtyarev continued efforts to improve his PPD design that resulted in the adoption of the PPD 40.  The PPD 40 used a drum magazine, which differed from that of the PPD 34/38 model, by having only feed lips at the top in place of a magazine extension mounted on the top.  This design improved feeding as the PPD 40 was designed only for drum magazines.  The PPD 40 was produced from 1940 to 1941, with approximately 87,000 being built.  The PPD submachine guns were manufactured before the widespread use of metal stampings and had many forged, machined parts that required a lot of tooling and skilled labor to produce.

A rare photo of an early PPSh 41 submachine gun with a tangent rear sight. Note that the detachable front sight hood is intact. (NARA)

The 7.62x25mm PPSh 41
The PPSh 41 submachine gun, and the pressed metal technology to produce it, was conceived by Soviet designer Georgiy Shpagin.  Shpagin was a former Russian army ordnance man who after his discharge began to work at the Kovrov Ordnance factory; the same facility where the PPD submachine guns were ultimately manufactured.  During August of 1940, Shpagin’s first prototype submachine gun was tested.  The weapon proved to be reliable under all conditions and its pressed steel, riveted and welded construction required few skilled workers or specialized machine tools to produce.  The PPSh was adopted in December of 1940 as the M1941 Shpagin submachine gun or Pistolet-Pulemyot Shpagina.  Production began during the fall of 1941.

PPSh 41 production was first organized in a network of factories around the Moscow area, each making parts or subassemblies to be assembled in centralized plants.  Initial production was slow but soon grew exponentially.  There were many companies involved in making PPSh 41 weapons and parts, including a few who had no previous experience with weapon manufacture, these including the Moscow Automotive Factory Zavod imeni Stalin (ZIS).  The ZIS factory symbol was a Cyrillic character that looks like a number 3, which represents the Roman letter Z.  Another PPSh 41 factory was the Scetmach plant in Moscow that marked their receivers with a Cyrillic letter C that translates to the letter S.  Other factories contributing to the production of the PPSh 41 submachine gun were: the Kirov Aviabuilding Plant, the F. Dzerzhinskly Factory, the Korov Plant, the Krasnuj Stamping Plant, the Tbilisi Instrument Factory, and the Tbilisi Train Factory.  However, by October, due to the advancing German army, many of the factories were abandoned and relocated to the Vyatskie Polyany Machine Building Plant.  The designer Shpagin was appointed as the chief designer of the facility, which became one of the primary manufacturers of PPSh submachine guns during the war.  The PPSh drum magazine manufacturing plant, originally located near Moscow was also forced to relocate to the Vyatskie Polyany area.  Many Soviet made PPSh drums and some box magazines will have the Star in a Shield trademark of Vyatskie Polyany plant.

An early manufacture Soviet PPSh 41 submachine gun with a tangent rear sight (top). The clip-on type front sight hood is missing. The magazine is an early production box type. (Private collection). Below it is a 1944 dated Soviet PPSh. The rear sight is a simpler two-leaf type with a U-shape notch. One leaf is calibrated for a 100 meter range, the second for 200 meters. The sight leaves are well protected by large side ‘ears.’ The front sight hood is spot welded to the barrel shroud. The receiver pivot pin is the late two-piece style. The top of the magazine well area of the trigger frame now has reinforcing extension tabs that partially envelope the receiver. Note the reinforcing bolt in the wrist of the stock. (National Museum of the Marine Corps)

The PPSh 41 consisted of eighty-seven separate parts, twenty-four of the parts were fabricated from pressed carbon steel, and only five of the components were forgings.  The four-groove chromium-lined barrel was pressed and pinned to the receiver.  The receiver extended out to form a sheet metal barrel shroud with cooling slots.  The end of the shroud formed a compensator to reduce muzzle climb.  The receiver was hinged at the front; at the back of the receiver was a spring-loaded end cap that had an L shaped lug at the bottom that secured it to the trigger frame.  By pushing the end cap forward the lug was disconnected from the trigger frame and the receiver could be lifted upward for maintenance, pivoting on the front hinge.  The bolt had a fixed firing pin and a cocking handle safety that could secure the bolt in an open or closed position.  The submachine gun was capable of both semiautomatic and full-automatic fire, with an automatic cyclic rate of 900+ rounds per minute.  The sliding mode of fire selector is located inside the trigger guard, forward of the trigger.  The full automatic position is forward, semiautomatic to the rear.  The weapon operates from an open bolt. The ejection port is located in the center of the receiver and spent cases are ejected straight up.

The Czech arms industry made a great impact in 20th century weaponry history with a large range of remarkable products.  Probably the most original of them all was a “special submachine gun” named the Skorpion, a successful effort for covering the gap between service pistols and traditional submachine guns chambered in pistol cartridges.  The Skorpion, in its initial, less powerful caliber, i.e. 7.65mm Browning (.32 Auto), has not met modern security unit’s requirements for some years, much less that of the armed forces; nevertheless its position as a globally respected legend has not been changed by this in any way.  It is therefore no surprise that Česká zbrojovka a.s., the manufacturer of the Skorpion, registered the name Scorpion as a trade mark in the 1990s and that it is currently using it now for the third generation of compact automatic weapons made in the town of Uherský Brod.

At the beginning of the initial Skorpion development was an interest of the then Czechoslovak Ministry of Interior in “a special submachine gun for service purposes” in cal. 7.65mm Browning (.32 ACP), which would be suitable both for so called special security activities, and for unified armament of the State Security and Public Security members.

Let us recall that the State Security (StB) was the secret political police of then socialist Czechoslovakia and the Public Security was the Czechoslovak version of uniformed police; under “special security activities” it is again necessary to look for intelligence and counterintelligence activities.  What kind of automatic weapon could suit such different requirements?  The Czechoslovak Ministry of Interior had about it a surprisingly clear vision, which it summarized in 1958 in the following requirements:

– cal. 7.65mm Browning (.32 ACP),
– weight 1 to 1.2 kg,
– overall length with shoulder stock folded 250 mm,
– overall length with shoulder stock extended 440 mm,
– height with pistol grip 150 mm,
– effective range of fire 100 m,
– two types of magazines – one for 8 to 10 rounds, the other for 20 to 25 rounds.
– besides fully automatic fire there should be provision to shoot also in single shots so “that this SMG could also fulfill the function of a pistol.”

It is obvious that such a clear and original vision had to go through a comprehensive research and analysis phase, the content of which we can only guess.  An interesting detail was the caliber chosen as it is highly unusual for an automatic weapon and additionally not quite suitable due to its relatively low performance and cartridge case with protruding head rim.  From today’s perspective one wonders if the choice of the 7.65mm Browning (.32 ACP) cartridge, which is often considered to be the greatest shortcoming of Skorpion submachine gun, what the Ministry of Interior had in their explicit intentions.  This cartridge on one hand represented a standard pistol caliber of the Czechoslovak Security Forces, and on the other hand it had several features which were ideal just for “special security activities.”  And just for this reason even the Czech Army did not mind it – but more about this later.

Task for Mr. Miroslav Rybá et al
In the first half of the 1950s within the centralization of the nationalized industry in Czechoslovakia came the end of the famous independent design offices of individual arms factories.  Instead, the Communist Party of Czechoslovakia decided to build a large specialized research and development centre, which was initially named Konstrukta Brno (after its place of residence in the City of Brno) and by the end of 1955 the elite of the Czechoslovak design engineers concentrated there dealt with military weapons and ammunition up to 30mm and anti-tank recoilless weaponry.  (Concurrently there was formed a small design centre in Prague specializing in the development of civilian firearms.  This centre however lost its independence quite quickly.)

New strict rules on confidentiality have been put into force for contracting weapon development and, besides other things, it has been out of question that the Ministry of Interior itself would address relevant design centre.  The application should first have to be submitted to the Czechoslovak Ministry of National Defence (MND), and in the case of the future Skorpion submachine gun this happened in the fall of 1958.  Relevant experts from MND found this idea of their colleagues from the Interior very interesting and the decision had been made that after production commenced, the purchases would also be by the Czechoslovak Peoples Army.  For the start, military personnel claimed only a small number of units for their intelligence units, however right in the beginning they came with important comments, observations and requirements, which had a substantial influence on the final version of the Skorpion.

The requirement of the Ministry of National Defence to produce a “special submachine gun” (among soldiers also known as “multi-purpose”) was sent to the Brno firearms research and development centre at the time when the engineers on the site were swamped with work.  All the senior engineers were busy completing other projects, such as the UK vz. 59 multi-purpose machine gun or the vz. 58 submachine gun (which in fact was and is the assault rifle, but the Czech military terminology did not accept this term at that time).  Due to their overload, the task to develop a new special submachine gun was assigned to Ing. Miroslav Rybář (1924–1970) who worked at the small-bore arms design department.  This turned out to be an extremely fortunate decision.

Ing. Rybář was a talented engineer with exceptionally deep technical skills and credentials from civil and military area.  He had been involved in firearms design since 1948, but had until then served only as a team member, supervised by senior engineers.  The Skorpion was to be his first individual project, the pinnacle of his career that, unfortunately, ended prematurely.

Unlike previous generations of firearms designers, who considered mathematical calculations a dull part of their work and delegated them gladly to others, Rybář started with a comprehensive theoretical analysis.  In fact, he wrote his doctoral thesis on the Skorpion, and presented it successfully at the Military Technical Academy in Brno in 1958.  With such a sound background, the development of the new type of a special submachine gun, aptly named Skorpion, proceeded really fast: lasting only from February 1959, to summer of 1961.

It is worth mentioning that although Rybář was undoubtedly the main architect of this new weapon he was not alone who was involved in this project.  The team counted as many as 13 engineers and we have to mention above all Otakar Galaš (1904–1968).  Galaš was well known as a designer of hunting and sniper rifles (the most famous worldwide being ZG 47 rifle).  Galaš contributed substantially to the development of the Skorpion – not only he was in charge of the sound suppressors’ elaboration and the weapon’s accessories, but having enlarged the barrel bore twist rate he also satisfactorily solved the accuracy of the 7.65mm Browning (.32 ACP) cartridge at distances between 25 to 150 m.  Moreover he became an excellent advocate of the new weapon.  Galaš found a very original way of demonstrating that the Skorpion could be carried covertly underneath one’s clothing: he came to a meeting bringing the submachine gun stuck in the shoulder holster underneath his jacket without anyone noticing it.  During the meeting, when he suddenly opened his jacket and took out the gun, there was no doubt that the Skorpion was suitable for concealed carry.  Jiří Čermák (1926–2006), another legend among firearms designers, who had his name indelibly recorded in the history of weaponry with already mentioned vz. 58 submachine gun, also helped Rybář with this project.  Although Čermák did not work on the Skorpion directly, he was the co-author of one small, but very smart structural element and he claimed the key idea of implementing rate-reducing mechanism.  However, the practicalities of design engineering were taken over by Rybář.

Between Pistol and Submachine Gun
The outcome of Rybář and his team work was a weapon that combined in a unique way the features of both submachine gun and pistol.  The common feature with the submachine guns was first of all the blowback (unlocked) breech, a magazine located in front of the trigger guard and folding stock that enabled shooting from the shoulder.  At the same time the Skorpion used the same cartridge as pistols, and to the certain extent, it was provided with a similar hammer-striking mechanism and the option to fire with the bolt in the forward position, which rendered shooting much more accurate when firing single shots.

For shooting in bursts, the high rate of fire and the muzzle climb were successfully tamed by the mechanical rate-reducer, which provided full control of the weapon also in the automatic mode.  (A certain role has to be attributed also to the weapon’s weight, which slightly exceeded initial requirement by the Ministry of interior, but still with a little exertion enables efficient single-hand hold and with centre of gravity moved forward.)  Various rate reducing mechanisms had been known before, but Rybář´s patent belongs to the ones which were particularly well designed – quite simple be it in design or manufacturing process and at the same time absolutely reliable.

The basic version of the Skorpion was at the end covered by five Czechoslovak patents on behalf of Rybář.  Another four were registered for the following development of variants in other calibres, one of which was additionally used in the series production.  Apart from the rate reducer, the patents covered the technical solutions of the shoulder stock, the trigger mechanism, the spring–loaded bolt stop, and so called retaining plate of the trigger unit which prevented hammer stop pin from falling out (co-author J. Čermák).

The original concept was applied particularly to the wire shoulder stock made from aluminium alloy.  The actual folding was realized around the rear part of the trigger unit with option for easy shoulder stock removal.  The length and stiffness of the shoulder stock due to the weapon compactness are in the limits of practical applicability, nevertheless, the manner of fixation and release in both utmost positions made for a wonderfully simple solution.  Ingeniously, the simple way of unfolding shoulder stock is with a single strike of the palm from the non-shooting hand, from below to the butt, whereupon the rest of the work is smoothly and reliably done by the shoulder stock pin spring, it is hard to find any comparisons.