The Stechkin OTs-38 Silenced Revolver

[Vikram]

I have not come across a similar revolver so far. To say exceedingly interesting is an understatement. Very ingenious too.

The StechkinOTs-38 Silenced Revolver:

http://www.kbptula.ru/index.php?option= ... 84&lang=en








Text from here

The OTs-38 (ОЦ-38) revolver is one of most unusual revolvers ever made. It was developed by the TSKIB SOO (Central Bureau for Sporting and Hunting Arms, a division of famous KBP organization, located in Tula, Russia) on request from Russian FSB (Federal Security Service). Because of its specific nature, OTs-38 is a limited production item, and it is being used by various Special Purpose law enforcement units. The OTs-38 is an integrally silenced weapon, which produces almost no sound and absolutely no flash upon firing. It is built as alternative to PSS silent pistol, and uses same special, integrally silenced ammunition known as SP-4. The OTs-38 is one of the last designs by the late I. Ya. Stechkin, a famous Russian gun designer.
OTs-38 resembles a traditional double-action revolver but it has many uncommon features. For the start, it has a more or less common exposed hammer with double-action trigger, but the action fitted with ambidextrous manual safety which allows for safe "cocked & locked" carry, for fast and accurate first shot. Next, the OTs-38 fires from the bottom chamber of the cylinder, as opposed to most revolvers that fire from upper chamber. Therefore, the barrel axis of OTs-38 is relatively low and muzzle jump is minimal. The large cylindrical housing, located above the barrel of OTs-38, contains an integral laser pointer / sight. The cylinder fixture is also of most unusual nature. The cylinder axis is hinged to the frame at the front, so once cylinder release (at the left side of the frame) is pushed forward, the cylinder can be swung open to the right and forward (while on most modern revolvers cylinders are swung down and to the left). Upon the opening of the cylinder, an automatic ejector partially withdraws the clip with rounds (or empty cases) from cylinder. This unusual cylinder mounting is essential to provide minimum play between the firing chamber in cylinder and barrel throat, since the SP-4 bullets are of pure cylinder shape, and thus cannot self-align itself with the barrel upon firing, unlike most conventional bullets that have conical or ogive nose shape. Since SP-4 ammunition is rimless, it is loaded into OTs-38 using special flat clips that hold 5 rounds together.
As said above, OTs-4 is fitted with integral laser sight. It is also fitted with traditional fixed iron sights, that have contrast white inserts.

The rimless SP-4 silent ammunition loaded into 5-round OTs-38 flat clip.


Best-
Vikram

[DAN]

Would like to know more about the "silent" ammunition. Looks like it fires just from the power of the primer.

[Grumpy]

I`m sure the cartridge used in this revolver was mentioned in a previous IFG topic .... What goes around, comes around I guess.
For details of the cartridge used and other `interesting` Russian guns and ammo check-out this link :
http://world.guns.ru/ammunition/russian ... ges-e.html

[timmy]

Very interesting!

The under-the-cylinder-axis barrel is used by others, but I do like the way the cylinder swings out. At first glance, it seemed like there was a large gap between the cylinder and the recoil plate, but with the "half moon" system of holding the cartridges, it makes sense.

WT they don't mention is the way the cylinder swings into the frame, but the side of the barrel is not relieved for the cylinder to pivot into the frame without hitting the barrel. Since the revolver is silenced and a big source of noise in a revolvers is the gap between the cylinder and barrel, and since it is a Russian revolver, and since there is such a vague description of the forcing cone,etc, I am suspecting some kind of gas seal design.

It would be interesting to handle one!

[TC]

Nice find Vikram,
Very close resemblance to the Mateba semi-auto.
The link doesn't say how they seal the gas. Personally however I don't think nothing can beat their own Nagant.

TC

[timmy]

Considering the gap between the cylinder & frame, and the similarity of the cartridge mouth to the original Nagant revolver ammo, and the need of the cylinder to clear the barrel, the actin must work similar to the original Nagant.

[Grumpy]

The revolver is not silenced and gas seal is of little consequence because it is the cartridge that is silenced using a piston/self-seal mechanism.

[Grumpy]

I`m sure it doesn`t use the Nagant sealing system because there is no need for a gas seal. There is minimal gap between the cylinder and the barrel - it fires from the bottom cylinder. What looks like a barrel at the `normal` location is the housing for a laser.

[Vikram]

It does look like the ammunition itself,SP-4, is silenced.

From the Worldgun.ru

http://world.guns.ru/ammunition/russian ... ges-e.html

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-1 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 S4M 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 200 m/s / 655 fps

More info from here:

http://pookieweb.dyndns.org:61129/cartr ... 4/sp-4.htm

The SP-4 is a unique type of cartridge. It builds on the Russian "piston driven" projectile design of older cartridges, and uses a "piston" to seal the gases within the cartridge. Therefore, no gases escape the barrel when fired, resulting in a silent discharge.

The piston seals against the case bottleneck. Presumably the gases slowly leak from the spent cartridge over time. The amount of powder beneath the piston is relatively small, as show by the cutout images. The tip of the piston centers the trailing end of the bullet.

The bullet appears to be no more than a slug of the wadcutter design with a brass/copper sleeve to align against the rifling:

Three distinct applications are made from this design - the first obviously being clandestine/SOF applications where silence is paramount. To this end, the Russians designed the SPP pistol for the ammunition. The pistol has a floating chamber with a 2nd buffer spring to eliminate metal-to-metal slap against the barrel and slide.

Best-
Vikram

[Grumpy]

It IS the ammunition that is silenced - it says so in the link I provided which you`ve just copied ! You didn`t provide the appropriate extract however :
.QUOTE: "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 with aluminum core extended back into the case to rest on the internal piston. Internally this cartridge contained a small charge of propellant behind a short 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. Earlies development centered on a large steel case with single-stage piston and internal firing pin, located in the base in attempt to keep high pgas pressures within the case after the discharge. This design was known as 7.62x63 PZ cartridge, which later evolved into PZA and PZAM cartridges of the basically same dimensions. This ammunition was in use since mid-1960s in S4M silent pistol. Later on, another cartridge cartridge, designated as 7.62x38 SP-3, has been developed and put in use during early 1970s, along with MSP two-barreled derringer type pistol and NRS scout shooting knife. The SP-3 featured much shorter case, because it used more compact two-stage piston system and more or less standard primers, securely crimped into the base of the cartridge. The performance of the SP-3 was about 25% less (in terms of muzzle energy) than of PZAM, but it was considered sufficient for its intended use in deep concealment last-ditch weapons used by Soviet secret intellegence agents outside of USSR.
Apart from all that, there is no provision for a silencer/moderator to be fitted to the revolver and no room for an expansion chamber plus baffles to be built into the revolver."
( .... goes and bangs head against brick wall ..... )

[timmy]

I`m sure it doesn`t use the Nagant sealing system because there is no need for a gas seal. There is minimal gap between the cylinder and the barrel - it fires from the bottom cylinder. What looks like a barrel at the `normal` location is the housing for a laser.

That the upper housing is a laser sight and the firing cylinder chamber is the bottom one is quite clear from the provided description.

I am noting again that, as the cylinder swings out, if there is minimal gap between the barrel and cylinder, the right side of the barrel needs to be relieved or the cylinder needs to move backward, or else the cylinder will jam on the barrel before it can be swung out.



The unique crimp on the Nagant revolver 7.62x38r cartridge has the purpose of projecting slightly beyond the cylinder to seal the barrel-cylinder gap when the cylinder is moved forward in the gas seal design.

The similarity between 7.62x38r and the crimp on the Stechkin cartridge, coupled with the wide gap behind the cylinder convinced me that this revolver is, indeed, of the gas seal design.

I am certain that my reasoning will not convince all who hold other views. However, I will let them take up the matter of the revolver's operation with one of the gun's sellers in the USA, Cheaper Than Dirt, in Ft. worth, Texas. Their description says:

This compact double-action revolver was designed by the late Igor lakovlevich Stechkin. Try to pronounce that name with a gut full of Vodka. This little baby uses a system similar to the Nagant revolver-the cylinder moves forward when the gun is cocked, tightening the seam between barrel and cylinder. And the OTs-38 uses specially designed 7.62x42mm silent ammo. The reduced volume of gases expended with the discharge of the OTs-38 makes for a very quiet gun and extreme accuracy.

from http://www.cheaperthandirt.com/mediapag ... ediaid=604

[Grumpy]

I get your point about the Cylinder having to move back to allowed it to swing in and out without fouling the barrel but still doubt that it uses Nagant type breech sealing. The comments by `Cheaper than dirt` are clearly in error anyway as they state that the cylinder moves forward when the gun is cocked - check the photograph above and you`ll see that the cylinder is forward with the revolver uncocked. A second point is that they state that the reduced volume of gases expended with the discharge ..... makes for a very quiet gun ...... If ANY gases were expended the gun would not be silent. The cartridge is specifically designed to not `expend` any gases and therefore does not require the revolver to have any form of gas sealing. A third point concerns the comment in the full article that "The gun can be loaded with loose ammo or five at a time with a metal clip". I think it may safely be assumed that the `metal clip` is an absolute necessity in order to fill the very large gap between the cylinder and the recoil plate.
Cheaper than dirt have no example of either the revolver or it`s ammunition for sale and it would seem that they are commenting on the gun only.

[timmy]

Stechkin OTs-38
Notes: The PSS is an excellent and successful silent pistol design, but it does have a weak point from the standpoint of deep black operations – it leaves behind shell casings unless the shooter stops to pick them up, something that is not always possible. As a result, the OTs-38 silent revolver was designed. The OTs-38 uses the same ammunition as the PSS – the 7.62mm SP-4, which uses a captive plunger system to silence the noise of firing inside the case. This silence is further enhanced by the use of a very old and not much used method of revolver operation – the gas-seal method. The gas-seal method, most often associated with the Nagant series of revolvers, is normally an unnecessary complication for revolvers that does little or nothing to enhance operation. On the OTs-38, however, it almost totally prevents the escape of firing gasses and sparks and gasses from the primer from being released from the gap between the cylinder and the barrel. This is done by the mechanism, which moves the cylinder flush with the barrel as the weapon is being fired. The result is a handgun which is almost as quiet as the PSS; the loudest noise is in fact from the hammer striking the firing pin.

from http://www.pmulcahy.com/special-purpose ... ndguns.htm

There simply is no reason to design a cartridge like that if the case mouth is not being used as part of a gas seal system.

I don't think that the "half moon clip" operates any differently than the originals did in the Colt and Smith& Wesson 1917 revolvers, and that is to provide positive headspacing for rimless cartridges.

In this design, there is an additional advantage that was also present in the original 1917 Design - they acted as a sort of speed loader. The original 1917 revolvers could have been made with a step in the chamber so the 45 ACP case could headspace on the case mouth as they do in the pistol. Ruger did that with their single action that came with interchangeable cylinders in 45 Colt and 45 ACP.

But the Ruger, being a single action, could use an ejector rod to remove spent cartridges, where the double actions could not - they needed the half moon clip to eject empty rimless cartridges. There is a shoulder (as opposed to a step) in revolver cylinders, and a 45 ACP case would only go in so far. Headspace may not be reliable, but this doesn't mitigate against the gun being fired at all.

In this Stechkin, even though headspace may not be perfect, I don't doubt that the gun can be fired without the clip, but it may not be as reliable.

I see the large gap between the recoil plate and cylinder as another evidence of a gas seal action. I've handled my brother's Smith & Wesson Model 25 enough to know that a gap that large, much less the rebated rear of the cylinder, is not necessary for half moon clip use alone.

But I still maintain that there is every reason to believe that such a cartridge is designed for gas seal operation. And while you do have a point about the Cheaper Than Dirt description, they sell more than enough Nagant 1895s to know what a gas seal action is.

I remain convinced that this Stechkin is a gas seal revolver. Perhaps you can find a review stating that it is not.

[TwoRivers]

Stechkin OTs-38



I remain convinced that this Stechkin is a gas seal revolver. Perhaps you can find a review stating that it is not.

Read Vikram's post. It's "gas seal" only as it seals the gas within the case. The bullet is not driven by the powder gases, but by the piston.

[TC]

Vikram, I studied the SP 4 ammo in detail on the net yesterday but could not post as I had to rush. The ammo is unique indeed and seems to have been specifically designed for assassination or serious injury from a very close range. But with so little powder being used to drive a piston forward and force the projectile out of the case and the barrel, the effective range cannot be too much. But cannot blame the designers. Most of their thought goes into keeping the gas sealed inside the case SAFELY once the cartridge is fired. More powder could blow the piston out too. This site says the muzzle energy is less than 600 fps and talks of industrial use for the SP 4.

http://pookieweb.dyndns.org:61129/cartr ... 4/sp-4.htm

Lastly, since there is no gas discharge, a number of construction- and field-demolition applications can utilize this cartridge as the basis for certain tooling. The examples in use are chain cutting tools that fire a round against a piston that cuts the chain, and rivet drivers similar to nail guns that use the round to drive a large fastener into the target... with underwater demolition, such a use would be to attach a demolition charge to an underwater mine without the use of magnets. Other uses can surely be found for this type of cartridge.

Posted stats:

Caliber, mm 7.62 x 41.5

Cartridge weight, 24 gram = 370.376 600 47 grain

Bullet weight, 10 gram = 154.323 583 53


Cartridge length, mm 42

Muzzle velocity, m/s 195 - 205 = 656 FPS

Max mean powder gas pressure, MPa 270 = 39160 PSI


Fire consistency at 25m range (R50), cm 5.5, max
Penetration range, m:
SSh-1 army helmet 25
four sandwiched dry pine boards, 25 mm thick 25

No wonder the FSB has found unique ways to utilize the potential of the cartridge... a single shot gun hidden inside a field knife for example ! (I want one of those )

I guess the same technology with a longer case and more powder would produce more muzzle energy. Lets see if they come up with a short barrel bolt action SILENT rifle with a new SP 4 anytime soon.

Thanks Vikram

Cheers
TC