The Stechkin OTs-38 Silenced Revolver

[timmy]

That there is no gas discharge is made evident by the design of the cartridge. It's obvious that there is no expanding gas discharged and no need for a silencer. I expect that the powder must be extremely fast burning, able to give the piston sufficient kick in a short distance to boot the bullet out of the barrel.

My assertion does not concern the design of the cartridge (other than the case mouth). I'm simply asserting that the lock mechanism of the revolver is a gas seal design. The fact that there are no gasses to seal with this cartridge is immaterial to my assertion; the designer has chosen to use the principle for other reasons.

[Vikram]

The discussion has been most informative,to say the least. Thank you all for your inputs.

Since I have Russian speakers very close to hand( ), I will ask one of them to translate my question into Russian and send it to the makers of this pistol. Hopefully, they will shed some light on how this revolver is silenced and if there are any design aspects to the revolver itself, other than the ammunition.

Thanks once again.



Best-
Vikram

[timmy]

Vikram:

If you are getting any sleep over there, one thing I would like to know: Does the shoulder of the cartridge headspace against the back of the barrel?

I wouldn't be surprised if this is the case.

[TwoRivers]

It headspaces against a shoulder in the cylinder chambers.

[timmy]

Have you seen one?

[TwoRivers]

Have you seen one?

No. Just cut-away drawings. Aside from the fact that looking at the picture of the pistol should tell it does not use the Nagant gas seal design. The cylinder is all the way forward with the hammer at rest. Only the cartridge to be fired is supported by the recoil shield, the remaining rounds have their bases unsupported except for the heavy clip.

[timmy]

Please refer to the operation of the M1895 Nagant revolver, as your statement seems to imply an analogy between the M1895 and the OTs-38 that does not, in fact, exist.

1. In the M1895, the breechblock which takes up excess space between the rear of the cylinder and the recoil shield, providing the proper headspace, is in place when the hammer is fully cocked and when the hammer is all the way down. The breechblock retracts to the recoil shield when the breechbolt piece (a separate part) is retracted by the trigger and hammer returning to the rebound position.

2. There is no analogous position on the OTs-38 to the M1895's rebound position. The rebound position that is in common double action revolver designs and is intended to keep the firing pin from touching off the cartridge in a loaded chamber underneath it. The OTs-38 does not have a rebound position. I am assuming that, in the absence of a hinged firing pin or the protrusion of a firing pin, the lock uses some sort of transfer bar system, perhaps similar to what Ruger uses, to keep the hammer from striking the firing pin unless the trigger is held back when the hammer falls.

3. Therefore, it is to be expected that the cylinder is all the way forward when the hammer is all the way down, as this would be the position the cylinder needs to be in when the gun is fired.

4. It is also expected that the breechblock is in place when the hammer is down.

5. It is expected that the breechblock is in place only behind the chamber aligned with the barrel, and no other, as in the M1895.

The dimension of the cylinder diagonally versus its simple height tells one that the opening in the frame must be large enough to accept the cylinder as it is swung in, which means that the clearance is too large when the cylinder is aligned with the barrel. This alone should tell that it must use a gas seal design (that is, the cylinder must move back to allow the cylinder face to clear the barrel when it is swung out of the frame, and must be moved forward when it is fired).

There are plenty of cutaway drawings of the M1895 Nagant, and descriptions of its operation. Are you saying you have a cutaway drawing of the OTs-38? Please, by all means, copy and post it if you do. I would welcome the opportunity to see it.

[timmy]

I have been trying to scour the internet for information on the OTs-38, and there really isn't very much that goes into great detail on this gun. I suppose that this is because it is meant for limited forces, alone, and most regular folks don't have access to it. One thing that came up is this page in Russian; maybe Vikram could find someone to read it:



http://popgun.ru/files/g/4/orig/1467167.jpg

The pictures give a nice display of the silent ammunition's principle of operation.

Here is a Russian reviewer's take on the OTs-38, which is informative but leaves out things I'd like to know about, and the google translate feature isn't always in top form. None the less, read it and see for yourself:

http://translate.google.com/translate?h ... 26rls%3Den

Here are some links to high resolution close-ups:

http://upload.wikimedia.org/wikipedia/c ... x-2011.jpg
http://upload.wikimedia.org/wikipedia/c ... OTs-38.jpg
http://upload.wikimedia.org/wikipedia/c ... x-2009.jpg

The last one gives good detail of the laser sight and how it is turned on and off.

Here is a discussion of the devolopment of silenced ammunition that is interesting:

http://translate.google.com/translate?s ... kiy_shepot

Here are some more high resolution pictures. The last one is VERY interesting!

http://weapon-men.ru/wp-content/uploads ... /ОЦ-38.jpg
http://russianguns.ru/wp-content/upload ... 250288.jpg
http://army.lv/large-photos/ots-38.27481.jpg

Note this last picture: you can clearly see the ridge in the cylinder chamber that forms a shoulder, against which, the cartridge will headspace. This means that the gun can be loaded without the charging clip and fired reliably, and that the functions of the clip are to load the gun quickly and to ensure positive ejection.

I thought that a gas seal was formed -- not for gas sealing, but instead because of descriptive language like this:

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.

I read into this too much and, from other descriptions, felt that some kind of perfect alignment was obtained by pushing the neck of the cartridge into the barrel, like the M1895 revolver. That this is not the case is clearly shown by the last picture linked, above. Cylinder alignment is obtained by conventional notches and a bolt, although it is possible (probable?) that the hand also presses the cylinder against one side of the bolt, as in the Schmidt-Galand action used by older Colt double action revolvers. More on this in a bit.

I have maintained that the OTs-38 uses a gas-seal mechanism and principle, not for sealing gas as in a M1895 Nagant, but to slide the cylinder forward. This statement http://zonawar.ru/rash_guns/rg_revolver_ots-38_eng.htmlseems to bear this out, although the translation into English does not make the point very clear:

The clip makes loading faster and easier, in order to maintain the gap between the cylinder and the barrel, necessary for free rotation of the cylinder, there is a special stop, which holds the cylinder to the rear when the finger is on the trigger without any significant trigger pull.

This blog has a similar statement, but worded differently, making me think that there is some translation ambiguity. I was unable to copy and paste from this page, so here's the link: http://blog.daum.net/eotjr0214/3457890

Regarding the gas seal type action, take a look at this picture:



http://army.lv/image.php?img=27483.jpg& ... 0&maxh=800

This clearly shows that the lower chamber, the firing chamber, has less distance between it and the recoil plate than does the upper part of the frame cutaway. This is an integral feature of the gas check design. Keeping the proper headspace when the cylinder slides forward means that the increased distance between the recoil plate must somehow be taken up. I believe that is why there is less space between the recoil plate and the lower chamber of the cylinder.

Brief explanation of the M1895 gas seal design:

Please note this picture:



http://i20.photobucket.com/albums/b245/ ... ant033.jpg

and this parts diagram:



In the picture, note the hammer-shaped part next to the mainspring, and next to it, a flat looking piece. The hammer shaped piece, #34 in the parts diagram, is the breechblock, and the flat piece next to it, #23 in the diagram, is the bolt piece.

their is a slot in the bolt piece that engages the very upper right bent arm on the trigger, which is the sear, so that when the trigger is pulled back, the sear arm will push up the bolt piece in a milled raceway, forcing the breechblock to pivot forward.

So, when the hammer is pulled all the way back to the single action cocked position, the trigger is also pulled back, and the breechblock moves forward.

Remember that, when the trigger is pulled back, the hand, which is also connected to it, pushes up and forward, rotating the cylinder and pushing it forward against the barrel.

When the trigger is pulled, either in double action or single action, all the way back, the breechblock remains forced forward by the bolt piece.

However, when the trigger moves forward to the double action (uncocked) position, the sear arm moves the bolt piece down and the breechblock retracts, allowing the cylinder to unlatch and turn. when the trigger is pulled again.

Now, the OTs-38 must have a totally different clockwork, required by using the lower chamber as the firing chamber. We cannot see those workings. However, in the pictures I've seen, there is no firing pin attached to the hammer, as in the M1895, Colt, or Smith & Wesson double action designs. There must be some sort of floating firing pin in the frame.

The hammer does not appear to have a rebound position, where the firing pin is retracted from the primer of the cartridge under it, but when the hammer is down, no firing pin is seen projecting out of the frame. I take this to indicate that some sort of floating firing pin and transfer bar mechanism is used, such as what Rugers have, so that the firing pin is only pushed forward when the trigger is pulled. This obviates the need for a recoil position.

The Russian M1895 is known for a stiff trigger pull, and no wonder: not only does pulling the trigger in double action turn the cylinder and cock the hammer, it must also operate the breech block and bolt piece, as well as pushing the cylinder forward. Similarly, I expect that all of the monkey-motion of the OTs-38's mechanism requires a fairly stiff trigger pull, as well, which is why provision is made to carry it cocked for single action use -- with an ambidextrous safety.

Normally, double action revolvers do have a stiffer double action trigger pull than single action, but it is not objectionable in use for someone who has practiced shooting double action. However, in this case, it was apparently felt necessary to carry the revolver cocked and use it in single action style -- at least, for the first shot.

As I contemplate all of this, I can't say the whole arrangement sounds very appealing to me as a shooter. A lot of trade-offs must be accepted, simply to not fling about empty cartridge cases. A pistol can be easily silenced and the mechanism is much simpler. Furthermore, I note that the point of keeping the empties from laying about the scene of use is to prevent "the other side" from knowing "who dun it." But with the unique bullet used by the silenced ammunition, surely even a basically skilled forensic team is going to figure out what kind of cartridge was used from the bullet alone -- how much does one actually conceal by carrying the empty cases away?

I suppose some logic must apply to all of this. Also, since the only thing one is supposed to hear when these silenced cartridges are fired is the working of the gun's lock, I suppose a revolver is more quiet than a pistol, as the pistol's action will work and make noise when it is fired.

Anyway, that's my take on the OTs-38

[russianshooter]

Sir its special silenced ammunition

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