KGB 7.62 x 42 MM SP-4 SILENT CARTRIDGE - JANES


#1

Anyone have one of these KGB “SILENT CARTRIDGES”? Talk about a neat design! I am curious, are they really silent?


#2

There is no such thing as a truly silenced firearm. You will always have the sound made by the mechanism itself and the sound of the projectile as it travels through the air. It’s possible to eliminate most of the sound but even a bow and arrow makes a sound. Ask any bowhunter how many animals he has missed due to the noise spooking them.

Ray


#3

Excellent point about the bow hunter. All ammo noise is relative. The quietest cartridge ever made to my knowledge was for the CIA dart gun previously shown. The only sound was the electrical contact with the primer which is very small. It would not scare a deer within 5 feet. The second quietest was the M1 bio/chem 30-06 which makes 2 clicks when fired.


#4

That makes sense and I figured they had to make some sound. But can they be “Quiter” bullets, equaling the noise output of say, a silencer? Also, the description says, “THE PISTON STOPS AGAINST THE INTERNAL CASE SHOULDER AND DEFORMS SLIGHTLY, THEREBY SEALING THE GASES INSIDE THE CASE”. Does that mean gases (or less gases) do not escape, and that is why they are quite? I am not 100% sure how a silencer works, but I think gases still escape after being diverted? Also, if the gas is “Sealed” in after firing, are the expended cases under pressure? Just curious.


#5

Check this post out. General Ammunition Collector Discussion ~ The smallest US flechette.

These pressure retaining cartridges are pretty noisy but not any where near the sound of a standard round. The pressure is retained inside the case for the instant of firing which is enough to “silence” the shot. It then leaks out . We developed this technology many years ago and decided against it as it turns a silent sentry ( or other target) into a screaming sentry in many cases. These shells are deployed mainly to attack small units and installations without raising the attention of major units in the area.


#6

Thanks! Makes lots of sence. The fact it held onto compresed gases after firing puzzeled me. Logical the gases would leak out. Otherwise, the spent cartridges could also be dangerous.


#7

Hello,

as long as it leaks subsonic …

Here is a lot of information about the russian silenced ammunition

world.guns.ru/ammo/sp-e.htm


#8

VERY VERY COOL! Thanks so much!


#9

A silencer and this cartridge type works in essentially the same way. It slows down the expansion of the gases to kill the “boom” made by the rapidly expanding gases. If you ever have a chance to hear a black powder cannon and a modern cannon fired next to each other or even a BP rilfe and a modern smokeless powder rifle of similar caliber you will hear the difference between CRACK of smokeless powder and the BOOM of black powder. The pressure and speed of the smokless powder media impact wave causes the much louder sound. A 25mm French AT gun sounds 10-20 times louder than a 12 pounder Napoleon cannon.

A silenced slows down the release of these gases into the air and thus reduces that wave. The gases are forced into the holes in the silencer as they attempt to get out of the weapon and equilize the pressure. In the silencer they are further slowed by some medium. Maxim used steel wool in his first ones. There are many kinds of medium used now.

In the case of the captive gas cartridges they also use the force of the expanding gases to push out the projectile. The case does not have to contain the pressure long and doesn’t. As previously stated it only has to be subsonic as it leaks out and it is.

This kind of cartridge is usefull in field operations and even some operations in large buildings or compounds. They are not of use in most covert operations in which propinquity is a concern. They are much too noisy.


#10

Really appreciate the great explanations!!! It was driving me crazzy, and not I understand how it works.


#11

Another key to understanding the pressure-silent ammo-silencer ideas is to consider the current tank guns. Most of the new tank guns have a bigger cylinder attached to the barrel 1/2 way or so down the barrel. It is a “bore evacuator”. It catches some of the pressure which is generated by the firing and releases it after the projectile is past. This pressure escaping out the barrel draws out some ( most?- AKMS should be able to speak to that) of the gases,smoke, etc. left in the barrel so that the gunner does not get a face full when he opens the breech for the next load. Both silencers and these capture cases do the same. In all the cases the pressure wave is released more slowly for effect.


#12

Now that I understood perfectly! Makes gobs of sense to me now. Nothing like a clean tank barrel! I think my AR15 rifle uses these gases in a similiar but different way with a tube connected to the barrel midway up and then back to the breech? I could be wrong with that analagy, but I understand the concept better. Thanx


#13

APFSDS

What you are referring to on the AR 15 rifle is, in fact, the operating mechanism. A portion of the propellant gas enters the gas port which is under the front sight, moves into the gas tube which directs it into the bolt carrier key causing the carrier to move rearward, unlocking the bolt. This all happens a lot faster than it took you to read it.

In large shipboard guns, all the extra propellant gas and other debris is blown out the barrel by a gas ejection system consisting of compressed air which is activated by a switch when the breech block opens. It makes more noise that the actual firing of the gun. Gunners Mates have a standard order that they use after a cease fire, “TURN THAT DAMN AIR OFF!”

Ray


#14

Thank you Ray! I did not know the big ship guns also used these gases to blow out their barrels. Really appreciate everyone explaining this stuff to me.


#15

Indeed, bore evacuators work as CSAEOD describes. They get “most” of the gunsmoke out of the barrel, but some does still waft out of the breech end of the gun when opened. You will find that tank crews will often keep the turret hatches open when firing to help ventilation in addition to the built-in ventilator. The gun barrel has three (if I remember correctly) ports on the top that are at about a 45 degree angle. When the gun is fired, the gas pressure fills the evacuator once the projectile is past, pressurizing it. When the projectile leaves the barrel and the pressure in the gun tube drops, the evacuator now can release it’s contents. As the ports are angled towards the muzzle, the gasses are pushed in this direction. This also creates a vacuum that helps draw the smoke from further down the barrel. An unintentional side effect of this vacuum, is that it is strong enough to help load a new round of ammunition into the breech. I never saw this done on the M1’s or M1A1’s, but it was an old tanker’s trick to “vacuum load” the gun on 105mm gunned M-60 series tanks to increase the rate of fire. The loader would load the gun and have a second round at the ready. As soon as the gun fired and the breech automatically opened, and while the bore evacuator was doing it’s thing, the loader would put the ready round into the breech opening and the vacuum would “suck” the round right out of his hands!

AKMS


#16

AKMS

Great post.

Ain’t that typical of a Gunner? Looking for a trick to make his life easier. :) :)

Ray


#17

Now that is awesome! I’d love to see a video of that :-)


#18

Thanks for the first person info.

Did you ever seen unburned case fragments still hot in the breech ?