The Talon P Moderator Design

[OldSpook]

I posted yesterday regarding my Talon P and got a question about the moderator.

Also posted about the rifle here earlier this month.

I ran the test on it today.
The video is plagued with wind noise and not really worth watching. The question was how well does it work?

I shot three shots with the moderator on the gun and then three without it. Here is the audio comparison.

Here is that audio slowed down to 1/8 speed and cropped to only the muzzle blast for each shot.

Here is the comparison graph of the signatures.

The RMS power for the moderated gun was 2.2 dBs less than the RMS power level for the unmoderated gun. That may not sound like much but your ears are telling you otherwise, aren't they?

That 2.2 dBs represents a TRUE 40% reduction in the total noise output from the moderator. That is quite good. Add to that the fact the signature (on the graph you can see it) is substantially shifted to the lower end of the spectrum. The net result is quite pleasant to the ear.

This is a very good moderator.
It is about 52mm by 91mm. It is very light. This image shows the moderator disassembled and laid out as it was disassembled top to bottom left to right.

The unit contains starting from top left moving in columns.

• attachment adapter
• clover shaped foam baffles (3)
• solid washer with a 8.2mm bore hole
• circular foam baffle
• another clover shaped foam baffle
• circular foam baffle
• endcap in the form of a cup with a 9.3mm bore hole
• moderator body

This moderator works much like the Weirauch/Huggette designs with two or three large chambers and sound absorbing baffles. The total volume of the moderator is about 196 cc which is considerably larger than the Weirauch on my HW110 (at about 116cc). It is not as effective either, in my opinion, however it has a much more pleasant tone and it is very, very quiet.

I like it.

 

[gendoc]

great write up there.....the talon-p i have is the new version with the larger trigger guard.
the moderator that was supplied with the gun didnt do much for the report of muzzle blast.
i bought the DFL adapter for 1/2x20 and purchased a STO Faux.
no further need for anything else.....its kinda like a $39 bb-gun from wal-mart
now....nothing but a phiffed !!!

 

[JungleShooter]

Thanks for running the test and interpreting the results, OldSpook!
Excellent.

Silencers are so fascinating!

Matthias

 

[beerthief]

really great when i slowed the speed down , Thankyou your research is tremendously helpful .

 

[OldSpook]

really great when i slowed the speed down , Thankyou your research is tremendously helpful .

I will take that audio and slow it down and stick it in there with the original audio. =)

 

[beerthief]

I will take that audio and slow it down and stick it in there with the original audio. =)

already can do that , click right side three dots then click speed , pick your speed . easy

 

[subscriber]

The unpleasant to pleasant conversion seems stronger to at real audio speed.

 

[Mike_Lenardon]

I posted yesterday regarding my Talon P and got a question about the moderator.

Also posted about the rifle here earlier this month.

I ran the test on it today.
The video is plagued with wind noise and not really worth watching. The question was how well does it work?

I shot three shots with the moderator on the gun and then three without it. Here is the audio comparison.
View attachment 420746

Here is that audio slowed down to 1/8 speed and cropped to only the muzzle blast for each shot.
View attachment 420809

Here is the comparison graph of the signatures.
View attachment 420748
The RMS power for the moderated gun was 2.2 dBs less than the RMS power level for the unmoderated gun. That may not sound like much but your ears are telling you otherwise, aren't they?

That 2.2 dBs represents a TRUE 40% reduction in the total noise output from the moderator. That is quite good. Add to that the fact that the signature (on the graph you can see it) is substantially shifted to the lower end of the spectrum. The net result is quite pleasant to the ear.

This is a very good moderator.
It is about 52mm by 91mm. It is very light. This image shows the moderator disassembled and laid out as it was disassembled top to bottom left to right.
View attachment 420750
The unit contains starting from top left moving in columns.

• attachment adapter
• clover shaped foam baffles (3)
• solid washer with a 9.3mm bore hole
• circular foam baffle
• another clover shaped foam baffle
• circular foam baffle
• endcap in the form of a cup with a 9.3mm bore hole
• moderator body

This moderator works much like the Weirauch/Huggette designs with two or three large chambers and sound absorbing baffles. The total volume of the moderator is about 196 cc which is considerably larger than the Weirauch on my HW110 (at about 116cc). It is not as effective either, in my opinion, however it has a much more pleasant tone and it is very, very quiet.

I like it.

I have 3 TalonP carbines. One original in .20, one of the new styles in .25 and one I put together myself wearing a Sumo and slinging .177s.

I agree with you that the new mod actually works. And works well at that, I was impressed and happy. The original really didn't work very well. At least untill I made some inserts for the baffles. Now my dogs lays around undisturbed.

I always look to see what you have to say about sound moderating. Thanks for sharing, please don't stop.

 

[pnwairgunner]

I wrapped it in that camo pattern stretchy tape stuff that’s sort of like an ace bandage. This covered the holes in the shroud and it has made a very noticeable change in the sound level.
Have you tried taping the holes up on yours?

 

[OldSpook]

I wrapped it in that camo pattern stretchy tape stuff that’s sort of like an ace bandage. This covered the holes in the shroud and it has made a very noticeable change in the sound level.
Have you tried taping the holes up on yours?

I will check that

 

[OldSpook]

The unpleasant to pleasant conversion seems stronger to at real audio speed.

Yes, when you slow it down it changes the pitch. The second sample divides all frequencies by 8 so an 8khz tone sounds like 1khz and a 100hz tone becomes subaudible. You are also hearing the echos from nearby objects at the slower speed. It makes the sample sound "fuller".

 

[subscriber]

Echo is part of "gunshot signature". I might hear a centerfire rifle from 500 yards away. It is not loud at that distance, but still has the characteristic echo, including of the supersonic crack of the bullet reflecting off the ground and objects along its path.

So, for airguns, reducing the echo helps in making the sound seem more innocuous. The best way to do that is to reduce the primary blast intensity.

The projectile striking the target can sound like an echo of sorts. On Christmas day I heard a "phut........ting" sound, over and over, from 150 yards up the hill. Clearly someone got an airgun of sorts for Christmas, and was shooting into a trap with a steel back plate. It was not loud or disturbing, but a very characteristic sound. Something recognizable because of the dual event sound; leaving no doubt because of the repetition.

 

[OldSpook]

Echo is part of "gunshot signature". I might hear a centerfire rifle from 500 yards away. It is not loud at that distance, but still has the characteristic echo, including of the supersonic crack of the bullet reflecting off the ground and objects along its path.

EDIT: I just reread your post and I think I am wrong in assuming here that we are not talking about the same echo. Muh bad. Time to hit the fart sack.

I don't think we are talking about the same thing here. The "echo" I am referring to here is the sound of the muzzle blast (the uncorking event) being reflected from a "corner reflector" which is 26 yards from the shooting station. I know this is what it is because I have calculated the return trip time and it occurs on schedule at about 140ms with every shot measured. The timing only varies slightly with the temperature on the test day.

So, for airguns, reducing the echo helps in making the sound seem more innocuous. The best way to do that is to reduce the primary blast intensity.

Yes I think you are right but I'm not sure we are talking about the same "echo". Here is an audio sample I took when testing the porous moderator. Each shot signature has been edited to 150ms. The echo is readily visible in the first three samples. It is also present in the second three samples but harder to see. There are other echos in the data which are closer to the uncorking event. One is from the flat roof of the sample station at about 18ms. I should sit down with this and do an indepth analysis of one signature labeling everything... Oh wait, yeah, I did that a couple of months ago but I had to take it down because I posted it on my personal status page.

 

[subscriber]

I am talking about all echo related to shooting. Including sound from the muzzle reflected from hard flat surfaces some distances away.

With a muffler on a PCP, it does not just empty of air in one event; air surges back and forth inside. Each time the air surges between baffles inside, a bit more sound comes out the front (and through the outer walls), until the events are too weak to be noticed. Meanwhile the stronger of those sound generating events bounces off hard flat surfaces in front of the muzzle in a manner that can be heard and captured. The further away, the more separation in the sound between the muzzle and the hard object the sound reflects off.

So, I mean that gunshots have a particular reverberation to them that makes them "ear-catching". A good muffler will removes the aspects caused by the abrupt pressure drop of gasses from the muzzle. Obviously there is nothing a suppressor can do about the sound the projectile itself makes - most obvious if supersonic.

As for being able to hear echo without seeing it in a sound capture trace, I hear more than three cycles of echo when I clap my hands once, with sound bouncing between the walls of the room I am in. I am sure it carries on longer than three cycles, but is too quiet to matter after that.

When I listen to a sound recording or airgun shot video, the extent of the echo is what suggest how loud the muzzle blast was to me, as any sound capture with auto leveling or level clipping does not sound loud via the speakers.

An example of this is the video of IMADMAN shooting his Huben pistol bare nuzzle and comparing it to various mufflers. Bare muzzle was sharp, with a noticeable echo. Muffled was a duller sound, without noticeable echo.

This is similar to reading how far away a large firework (or ordinance) is from you via the tone, rather than the intensity. Also, whether or not there is a strong echo suggests a rifle over a handgun; although that is not foolproof. While we are at what sound quality gives away: snap...pop suggests incoming - assuming supersonic projectiles; with pop and snap blended suggesting outgoing (or incoming subsonic handgun);

As for the contention that we may not be talking about exactly the same thing; so what? As long as you say what you mean; and I say what I mean. If we agreed exactly about everything, there would be little point in saying anything.

 

[OldSpook]

Yeah after a reread of your post I understood what you were saying about echo.

Regarding your comments about incoming and outgoing. I served.

I don't trust my ears. They have experienced far too many explosions and muzzle blasts to be reliable for much more than simple conversation.

I agree that echo can only be mitigated by suppressing the muzzle blast.

 

[subscriber]

I figured that you knew the difference between incoming and outgoing. I was a conscript in South Africa back in the 1980s. That was where I came to appreciate the sound signature of rifle bullets coming towards me.

 

[OldSpook]

I figured that you knew the difference between incoming and outgoing. I was a conscript in South Africa back in the 1980s. That was where I came to appreciate the sound signature of rifle bullets coming towards me.

You know when we sort of kicked around the idea of vents in the sides of moderators?
Then in that other thread I mentioned that moderators were directional. Well of course you know that as well, but what about the possibility of reducing the directionality of a moderator design. Sure it might be louder to your ears but the overall detectable range might be reduced if you distributed that energy more uniformly. I'd be interested in your thoughts along that line?

 

[subscriber]

OldSpook,

Making a muffler less directional sound like a viable idea. It does not have to be overly loud to the shooter, providing they cannot "see" the inside or outside edge of the side vents. If you take a look at muzzle brakes on .50 BMG rifles, most of them direct gas flow somewhat rearwards to reduce recoil further; but the outlets to the ports are masked by tapering the overall structure smaller towards the front. The brakes that do not have that taper are brutal with respect to concussion at the shooter's face.

Rather than taper the airgun muffler, I would consider shrouding the the vents with low semi-circular walls at each vent, so neither of the shooter's ears have "line of sight" to the inside "tube", or outside edge of the vents.

Rather than making the side vents all radial, they can be angled in a "sweep" to make the sound even less directional. But all of the vents, including ones pointing perhaps 45 degrees towards the rear should have their own little walls to protect the shooter for discomfort.

If I can get over my résistance to tapering the OD of the muffler, that taper could be curved, rather than a straight cone. That way all the vents could be perpendicular to the surface around them, yet be arranged in a "sweep" so none of the vents would be parallel, for maximum angular dispersion. Certainly the straight or rounded cone designs would involve the least amount of work to design.

If you need pictures to visualize what I am trying to describe, and can do some designs so we can contemplate feasibility. Even as I type this, I have figured an easy way to sweep the vent angles in a circular path, without making the OD of the muffler conical - at least in the finished part. I might have to design something now

 

[subscriber]

My last post meandered a bit, so let me start with images of the directional reducing diffuser concept muffler. It does not have any features to protect the shooter from increased rearward blast (yet). The vents pointing back in the last row are at 45 degrees beyond pure radial. So, nasty for the shooter's ears in this concept design. The inside "tube" and front outside edges of those vents will reflect sound back at an even shallower angle, so any implementation of the idea is screaming for help to shield the shooter's ears - coming later.

Also, the ability to print the part standing on its front end will need to be restored via external supports. (Or a cylindrical design that has a swept hole pattern) Printing with the mounting thread down will collapse the internal cones; so that is not viable.

Anyway, consider this design purely as a goal statement, to spread the sound spherically, to make the sound less directional.

The vent holes are 2.5 mm in diameter as shown, but should print closer to 2 mm when FDM is used.

 

[subscriber]

I have taken the spherical head muffler above and made the head conical, to mask the shooters ears from side vent blast. Also, the conical head muffler has a flat front to aid in FDM printing without supports. This while to print the spherical head muffler would require external supports to be used under the rounded head.

While I am at it, I have included the 7.5m baffle bore "parent design" muffler as a control, for anyone interested in printing these "directionality-confuser" vented head mufflers. The STLs for all three of the muffler shown below are contained in the same attached ZIP file, below. Apart from measuring dB in front of the mufflers, and from the side, I would recommend comparing loudness measured at the shooter's ear, closest to the back of the muffler head.

Printing any of these three mufflers requires they be printed threads up, or the internal cones will fail to print correctly. Hence, the spherical head version will require external supports be turned on in the slicer.

View attachment Diffuser Vent Study STLS.zip

Function:
From the first image below: The conical head shields you ears from being near coaxial with any of the vents when shooting, compared to the round head muffler. Also, just being able to see a vent inner tube surface, or outer edge of the hole means that some shock will be reflected towards you. This is clear when comparing the round head to the cone head - even at a 12 degree angle off coaxial. Depending on your sight over bore distance it may be possible to make the cone smaller to achieve the desired masking effect.