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Now here's my informative post...(from www.world.guns.ru)
S-4M silent pistol (USSR / Russia)
Type: Single Action
Calibers: 7.62x63 PZ / PZA / PZAM
Weight unloaded: n/a
Length: 140 mm
Barrel length: 88 mm
Capacity: 2 rounds
The S-4 (and its latter modification S-4M) pistol is a further development of the concept, first used in Soviet MSP pistol. However, the S-4 pistol was apparently developed with military users in mind, as it traded some concealability for more power and range, thanks to much bigger and more powerful silent cartridges of PZ family. It has been developed during mid- or late 1970s, and has been used in Afghanistan and latter campaigns, as well as in many counter-terror operations of last decade.
The S-4 / S-4M pistols are derringer-type, two barreled firearms, with the barrels stacked one above another. For reloading, rear part of the barrel block is tipped up, and cartridges are loaded or manually extracted using special spring-type clip, which holds two rounds together. Trigger is of a single action type for improved accuracy, enclosed hammers are cocked automatically when barrels are opened for reloading.
Special purpose small arms ammunition of USSR and Russia.
© 2005 Maxim Popenker
SP-3 and PZAM silenced pistol ammunition
During the postwar period, there was much development in the field of the small arms ammunition. Soviet Union actively participated in these developments, following both mainstream and some more or less unconventional routes. The mainstream developments are well known and included 7.62x39 M43 and 5.45x39 M74 intermediate ammunition for assault rifles, as well as 9x18 ammunition for pistols. Of cause, there was much more development in these lines that it might appear at the first sight, but for now we will focus on rather more interesting types of ammunition.
During the post-war decades both USSR and its major rivals from NATO were deeply engaged in espionage and counter-espionage. These activities sometimes called for very special actions, usually described by typical Russian euphemism as 'wet deeds', or, in plain language, murders. These clandestine operations required some very special weapons, and during early 1950s the designer Igor Ya. Stechkin (better known as an author of the 9mm APS Stechkin automatic pistol), developed a very special weapon for KGB. Externally this weapon looked much like flat tin cigarette case, but internally it held three short barrels and a trigger unit. The intended use of this weapon was obvious, but the necessary compact size effectively prohibited the use of a standard silencer. As a result, Stechkin developed a special type of ammunition, which required no silencer to be fired silently. The major source of the sound of gunshot is the large volume of hot gases, violently expanding from the muzzle and creating a sound wave. Stechkin avoided this problem by encapsulating the blast of the propellant within the cartridge case. First experiments were conducted using standard 9x18 cases, but the ammunition, designated SP-1 (Spetsialnyj Patron 1 - special cartridge 1), never achieved production status. The SP-2 ammunition, which was the first to be produced in any quantity, has been based on 7.62x39 case, slightly shortened and fitted with round-nose 7.62mm bullet (most probably similar to one used in 7.62x25 TT cartridges). Internally this cartridge contained a small charge of propellant behind a two-stage telescoped piston, which propelled the bullet out of the case when fired and then locked the hot powder gases inside the case. The resulting sound was almost non-existent, and the cartridge has been adopted by KGB for clandestine operations. To improve performance and somewhat confuse possible investigators, the round-nose bullet has been later replaced by standard pointed 7.62mm bullet originally used in 7.62x39 M43 ammunition. This cartridge, designated as 7.62x38 SP-3, has been in use since early 1970s, along with MSP two-barreled derringer type pistol and NRS-1 scout shooting knife. While the SP-3 cartridge was more or less adequate for clandestine work of KGB, it was way underpowered for use by elite Spetsnaz units, which were supposed to operate deep behind enemy lines. To provide Spetsnaz with more potent weapon, Soviet designers developed an enlarged version of SP-3 cartridge, initially known as PZ, which latter involved into PZA and PZAM 7.62mm silent cartridges. Used in S-4M 'Groza' (Thunderstorm) two-barreled break-open pistol, the 7.62x63 PZAM cartridge has a very strong, thick walled, slightly bottle-necked case with two-stage telescoped piston, similar to SP-3. It is loaded with the same 7.62mm pointed M43 bullet. It has been used by Soviet Spetsnaz forces in Afghanistan.
SP-4 silenced ammunition
The key problem with the SP-3 and PZAM ammo were their telescoped pistons, which projected significantly from fired cases and thus made almost impossible to develop the semi-automatic weapons for these cartridges. During late 1970s and early 1980s soviet designers solved this problem by developing the 7.62x42 SP-4 ammunition, which used the same basic principle. The telescoped two-stage piston has been replaced by single-stage piston, which did not projected from the case when fired; the standard 7.62mm M43 bullet has been replaced by the cylindrical bullet, made of mild steel, and fitted with a brass driving band at the front. This cartridge has been adopted circa 1983 by KGB and Spetsnaz elements of the Soviet Army, along with six-shot, magazine fed, blowback operated semiautomatic PSS pistol and single-shot NRS-2 scout shooting knife. The SP-4 ammunition and PSS pistols are still in use by elite Spetsnaz units within Russian armed forces, as well as by some FSB and MVD elite units. Apparently, the earlier MSP pistol with SP-3 ammo and SP-4M pistol with PZAM ammo were not phased out of service and still can be encountered in the hands of serious operators, who not require multi-shot capabilities of PSS / SP-4 system.
cartridge metric designation bullet weight muzzle velocity
SP-4 7.62x41 9,3 g / 143 grain 270 m/s / 885 fps
7.62mm SP-4 silent cartridge (left) compared to 9x19 Parabellum cartridge (right)
SP-5 and SP-6 subsonic assault rifle ammunition
Next line of development, also initiated by Spetsnaz requirements, also involved silenced weapons, but in more powerful form. Since the effective range of silenced pistols is severely limited, scout and Spetsnaz elements of the Soviet army originally employed AK and AKM rifles, fitted with detachable sound suppressors (silencers) and loaded with special versions of 7.62x39 M43 ammo, known as 7.62x39 US (Umenshennaya Skorost - Low velocity). To achieve subsonic velocity along with acceptable ballistics, these cartridges were loaded with heavier bullets, but its performance was still inadequate. So, during the late 1980s, soviet designers developed improved sub-sonic ammunition, suitable for specially designed automatic weapons. These cartridges, known as SP-5 and SP-6, were based on a 7.62x39 M43 case, necked-out to 9mm, and loaded with heavy, streamlined bullets. The SP-5 cartridge was loaded with standard 'ball' bullet with lead core, and was intended for accurate sniper work out to 300-400 meters. The SP-6 cartridge featured an armour-piercing bullet with hardened steel core, which could defeat typical military type body armour at the ranges of up to 300-400 meters. Two weapons were initially developed for this ammunition, both based on the same receiver and gas operated action - VSS sniper rifle and AS assault rifle. Both weapons were selective fired, with integral sound suppressors, and used same magazines with 10- or 20-round capacity. Latter on, several more weapons were developed for 9x39 ammunition, such as SR-3 and 9A-91 compact assault rifles, used by elite Internal Affairs Ministry, Police and State Security units. The one problem, associated with 9x39, as well as with most other special purpose cartridges, is that such ammunition is usually quite expensive. An attempt was made during late 1990s to produce much cheaper 9x39 AP loading, designated as PAB-9. This cartridge featured bullets with stamped (instead of machined) steel cores, as well as increased driving surfaces. As a result, accuracy was poor and barrel wear significantly increased, so this ammunition is apparently no longer in use.
cartridge metric designation bullet weight muzzle velocity
7.62 US 7,62x39 12,5 g / 193 grain 290 m/s / 950 fps
??-5 9x39 16,8 g / 260 grain 280 m/s / 920 fps
??-6 9x39 16 g / 247 grain 280 m/s / 920 fps
I think this is the most ingeniuos gun/ammunition ever made.
S-4M silent pistol (USSR / Russia)
Type: Single Action
Calibers: 7.62x63 PZ / PZA / PZAM
Weight unloaded: n/a
Length: 140 mm
Barrel length: 88 mm
Capacity: 2 rounds
The S-4 (and its latter modification S-4M) pistol is a further development of the concept, first used in Soviet MSP pistol. However, the S-4 pistol was apparently developed with military users in mind, as it traded some concealability for more power and range, thanks to much bigger and more powerful silent cartridges of PZ family. It has been developed during mid- or late 1970s, and has been used in Afghanistan and latter campaigns, as well as in many counter-terror operations of last decade.
The S-4 / S-4M pistols are derringer-type, two barreled firearms, with the barrels stacked one above another. For reloading, rear part of the barrel block is tipped up, and cartridges are loaded or manually extracted using special spring-type clip, which holds two rounds together. Trigger is of a single action type for improved accuracy, enclosed hammers are cocked automatically when barrels are opened for reloading.
Special purpose small arms ammunition of USSR and Russia.
© 2005 Maxim Popenker
SP-3 and PZAM silenced pistol ammunition
During the postwar period, there was much development in the field of the small arms ammunition. Soviet Union actively participated in these developments, following both mainstream and some more or less unconventional routes. The mainstream developments are well known and included 7.62x39 M43 and 5.45x39 M74 intermediate ammunition for assault rifles, as well as 9x18 ammunition for pistols. Of cause, there was much more development in these lines that it might appear at the first sight, but for now we will focus on rather more interesting types of ammunition.
During the post-war decades both USSR and its major rivals from NATO were deeply engaged in espionage and counter-espionage. These activities sometimes called for very special actions, usually described by typical Russian euphemism as 'wet deeds', or, in plain language, murders. These clandestine operations required some very special weapons, and during early 1950s the designer Igor Ya. Stechkin (better known as an author of the 9mm APS Stechkin automatic pistol), developed a very special weapon for KGB. Externally this weapon looked much like flat tin cigarette case, but internally it held three short barrels and a trigger unit. The intended use of this weapon was obvious, but the necessary compact size effectively prohibited the use of a standard silencer. As a result, Stechkin developed a special type of ammunition, which required no silencer to be fired silently. The major source of the sound of gunshot is the large volume of hot gases, violently expanding from the muzzle and creating a sound wave. Stechkin avoided this problem by encapsulating the blast of the propellant within the cartridge case. First experiments were conducted using standard 9x18 cases, but the ammunition, designated SP-1 (Spetsialnyj Patron 1 - special cartridge 1), never achieved production status. The SP-2 ammunition, which was the first to be produced in any quantity, has been based on 7.62x39 case, slightly shortened and fitted with round-nose 7.62mm bullet (most probably similar to one used in 7.62x25 TT cartridges). Internally this cartridge contained a small charge of propellant behind a two-stage telescoped piston, which propelled the bullet out of the case when fired and then locked the hot powder gases inside the case. The resulting sound was almost non-existent, and the cartridge has been adopted by KGB for clandestine operations. To improve performance and somewhat confuse possible investigators, the round-nose bullet has been later replaced by standard pointed 7.62mm bullet originally used in 7.62x39 M43 ammunition. This cartridge, designated as 7.62x38 SP-3, has been in use since early 1970s, along with MSP two-barreled derringer type pistol and NRS-1 scout shooting knife. While the SP-3 cartridge was more or less adequate for clandestine work of KGB, it was way underpowered for use by elite Spetsnaz units, which were supposed to operate deep behind enemy lines. To provide Spetsnaz with more potent weapon, Soviet designers developed an enlarged version of SP-3 cartridge, initially known as PZ, which latter involved into PZA and PZAM 7.62mm silent cartridges. Used in S-4M 'Groza' (Thunderstorm) two-barreled break-open pistol, the 7.62x63 PZAM cartridge has a very strong, thick walled, slightly bottle-necked case with two-stage telescoped piston, similar to SP-3. It is loaded with the same 7.62mm pointed M43 bullet. It has been used by Soviet Spetsnaz forces in Afghanistan.
SP-4 silenced ammunition
The key problem with the SP-3 and PZAM ammo were their telescoped pistons, which projected significantly from fired cases and thus made almost impossible to develop the semi-automatic weapons for these cartridges. During late 1970s and early 1980s soviet designers solved this problem by developing the 7.62x42 SP-4 ammunition, which used the same basic principle. The telescoped two-stage piston has been replaced by single-stage piston, which did not projected from the case when fired; the standard 7.62mm M43 bullet has been replaced by the cylindrical bullet, made of mild steel, and fitted with a brass driving band at the front. This cartridge has been adopted circa 1983 by KGB and Spetsnaz elements of the Soviet Army, along with six-shot, magazine fed, blowback operated semiautomatic PSS pistol and single-shot NRS-2 scout shooting knife. The SP-4 ammunition and PSS pistols are still in use by elite Spetsnaz units within Russian armed forces, as well as by some FSB and MVD elite units. Apparently, the earlier MSP pistol with SP-3 ammo and SP-4M pistol with PZAM ammo were not phased out of service and still can be encountered in the hands of serious operators, who not require multi-shot capabilities of PSS / SP-4 system.
cartridge metric designation bullet weight muzzle velocity
SP-4 7.62x41 9,3 g / 143 grain 270 m/s / 885 fps
7.62mm SP-4 silent cartridge (left) compared to 9x19 Parabellum cartridge (right)
SP-5 and SP-6 subsonic assault rifle ammunition
Next line of development, also initiated by Spetsnaz requirements, also involved silenced weapons, but in more powerful form. Since the effective range of silenced pistols is severely limited, scout and Spetsnaz elements of the Soviet army originally employed AK and AKM rifles, fitted with detachable sound suppressors (silencers) and loaded with special versions of 7.62x39 M43 ammo, known as 7.62x39 US (Umenshennaya Skorost - Low velocity). To achieve subsonic velocity along with acceptable ballistics, these cartridges were loaded with heavier bullets, but its performance was still inadequate. So, during the late 1980s, soviet designers developed improved sub-sonic ammunition, suitable for specially designed automatic weapons. These cartridges, known as SP-5 and SP-6, were based on a 7.62x39 M43 case, necked-out to 9mm, and loaded with heavy, streamlined bullets. The SP-5 cartridge was loaded with standard 'ball' bullet with lead core, and was intended for accurate sniper work out to 300-400 meters. The SP-6 cartridge featured an armour-piercing bullet with hardened steel core, which could defeat typical military type body armour at the ranges of up to 300-400 meters. Two weapons were initially developed for this ammunition, both based on the same receiver and gas operated action - VSS sniper rifle and AS assault rifle. Both weapons were selective fired, with integral sound suppressors, and used same magazines with 10- or 20-round capacity. Latter on, several more weapons were developed for 9x39 ammunition, such as SR-3 and 9A-91 compact assault rifles, used by elite Internal Affairs Ministry, Police and State Security units. The one problem, associated with 9x39, as well as with most other special purpose cartridges, is that such ammunition is usually quite expensive. An attempt was made during late 1990s to produce much cheaper 9x39 AP loading, designated as PAB-9. This cartridge featured bullets with stamped (instead of machined) steel cores, as well as increased driving surfaces. As a result, accuracy was poor and barrel wear significantly increased, so this ammunition is apparently no longer in use.
cartridge metric designation bullet weight muzzle velocity
7.62 US 7,62x39 12,5 g / 193 grain 290 m/s / 950 fps
??-5 9x39 16,8 g / 260 grain 280 m/s / 920 fps
??-6 9x39 16 g / 247 grain 280 m/s / 920 fps
I think this is the most ingeniuos gun/ammunition ever made.