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Posted: Mon Sep 03, 2012 2:12 am
by jackssmirkingrevenge
POLAND_SPUD wrote:damn that was a lenghty response
... but a valid one :)

Re: shut-off valve suppressor

Posted: Thu Oct 17, 2019 6:27 am
by jackssmirkingrevenge
I've been revisiting this idea in my head lately, maybe pistons would work as suggested earlier where a loose ball was less than ideal:

Image

Not shown are the return springs keeping the pistons in the "rest" position, as well as some sort of flow control screw in the porting in order to be able to tune the system.

Re: shut-off valve suppressor

Posted: Thu Oct 17, 2019 6:37 am
by wyz2285
The problem is in most cases we don't have such a nice bore and ammo fit. I can see it working with pellet guns as the pellet skirt should shut against the bore.

Re: shut-off valve suppressor

Posted: Thu Oct 17, 2019 11:14 am
by jackssmirkingrevenge
It apparently was made to work for firearms:

Image

This is a German "Kitzmann" design, quite an ingenious system!

The inner block moves forward pushing against the slanted front endcap, which forces the flexible part to close off the muzzle, like a pair of tongs.

Re: shut-off valve suppressor

Posted: Thu Oct 17, 2019 12:57 pm
by wyz2285
And what stops it from moving too early...?

Re: shut-off valve suppressor

Posted: Fri Oct 18, 2019 6:31 am
by jackssmirkingrevenge
wyz2285 wrote:And what stops it from moving too early...?
It seems to be finely balanced for a particular bullet weight and velocity, here is a translation of an article I found:
The Kitzmann suppressor is composed of a tube with end caps, the gas tongs, and a front block. The base of the gas tongs acts as a piston (with the tube acting as the corresponding cylinder), being driven forward by the gas blast following the projectile. This shoves the gas tongs against the front block's inclined surfaces, forcing the jaws closed, which seals off the gas flow. Once the pressure decreases the tongs open and, by pushing against the front block, return rearwards.

The system was designed for integrally suppressing a firearm, and needs quite a bit of gas to function. Hence, normal rounds are used. The barrel is ported inside the suppressor to reduce muzzle velocity to subsonic.

This requires a precise relationship between the amount of gas and the speed of the projectile. Given a fixed amount of gas produced, lighter projectiles lead to more "bang" due to the time between the projectile leaving the gun and the tongs closing being longer. Heavier projectiles can lead to the bullet being clamped by the tongs, bending them and ruining your fun.

The Kitzmann device makes an interesting snap-poof sound, with the whole thing being almost too short to differentiate the different elements. It needs relatively frequent cleaning, since fouling retards the forward movement of the tongs, and hence their closing.
I found Ernst Kitzmann's patent reference but it does not seem to be available online.

In doing so I found another patent that seems to use a system like the one I proposed with gas-actuated flaps that temporarily close the muzzle:

Image

No evidence of any prototypes though.

An interesting aside from Kitzmann is a proposal for a high strength cartridge that "enables more powerful powder to be used thereby achieving a more accurate firing, reducing at the same time loudness of report and recoil."

This is the firearm equivalent of using a timed valve at high pressure rather than a dump valve at low pressure.