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DIY moderator build

rkr said:
I tested AWT internals in a A&M Marksman and it was more quiet when I added felt. However, it might not make a difference if the shell is thick walled soft plastic pipe.
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This is one of the things I had some concerns about, my initial tests were done with baffles in a fairly thick walled plastic pipe, where as now I'm using a thin walled carbon fibre tube. The expansion chamber is the only thing being wrapped in felt for my first attempt. Sadly I can foresee me having to reduce the size of the baffles and fitting them inside a felt wrapped cage, but you never know, it might work as is.
 
Here's the results from my AWT tests, it actually worked very well with felt - much better than stock internals and big difference to results without felt which was worse than stock internals (5 shot averages at 12 fpe):

47941809396_8cffd28191_b.webp
test by abbababbaccc, on Flickr
 
I've always wondered, if anyone did three different sized chambers, felt covered rollers, then the outside of the moderator has small holes in the outer layer to let air/pressure escape.
 
Andy001 said:
I've always wondered, if anyone did three different sized chambers, felt covered rollers, then the outside of the moderator has small holes in the outer layer to let air/pressure escape.
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It's been done and it works, kind of. The trick is limiting the air exit or shall we say reducing the air speed so much that it doesn't make noise as such. Here's some data from an old test where I drilled six 4mm holes to the rearmost chamber of HW silencer.

35385719600_1bfa55db34_z.webp
silencer-test-with-holes_zps4e86f770 by abbababbaccc, on Flickr

As you can see it made more noise with holes but when I added second layer of felt under the original felt and small curler it got better.

What I've been wondering is the hole size. As we reduce the hole diameter the dB pressure peak moved to higher frequency. If we could move it to 20+kHz area then we could use that size holes without any extra felts and we could use quite a lot of them to release most of the pressure through the silencer walls. I've nasty manflu ongoing so I'm not going to be testing it now but if someone has some extra time in their hands ... make a plug for endcap, start by drilling 0.1mm hole and measure the pressure peak frequency and proceed from there on.
 
rkr said:
I thread them with 1/2" UNF tap if that's what you are asking? Do it on a lathe to have it straight or you will have clipping.
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I haven't got a lathe, I was buying 1/2" threaded inserts from eBay. They were fine but are a little heavy and a little long in length, so fills internal space inside the moderator.

Lathes and 3D printers are on my to get list
 
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I've built a few in the past and I've found that a three chamber design, long, short, long with curlers, 10 mm diameter, wrapped with the fluffy microfibre cloth, not the smooth glass cleaner type works better than anything.
 
This is my 2AM Silencer.
20221024_062540.webp

. its called the 2AM because thats what time its made for .
When there is No back ground noise . when you think you have a quiet Silencer take it out in the middle of the night. normal day time back ground noise will hide up to 45 percent of air gun noise .
Night time though its totally different.
My 2AM has 5 chambers the bores on the baffle alternate in size .
Volume of the Silencer is very important to.
having enough volume to let the discharge expand but still be contained with in the body is a must . this allows the pressure drop before it gets to the end of the Silencer.
ie ..less noise from lower pressure as the air is traveling slower 🙂👍
 
Background noise varies as does settings of your measurement devices, gun settings etc. That's why I never look at absolute values but always start by measuring a set with the gun I use and Weihrauch silencer and then measuring whatever silencer or mod I'm testing. That way I always have a baseline that I can compare things against.
 
First test carried out, I've not got a decibel meter so getting any semblance of "real" results is a bit difficult. In whichever case, it definitely does something! In a straight up test against an A&M twink it does sound a bit quieter, but at the same time it could just be a tonal change. Mine does seem to have a slightly higher pitch to it. I'll try and get a video. any who's here it it is!

Generally I think it looks pretty damn good with the glaring exception of the front cap, where the clear coat has gone all weird. I think I may have put too thick a layer on. only a 10 minute job to sand it back an re-apply so not an issue. It's 40mm diameter, 150mm in length and comes in at a featherweight 80g, the weight reduction is definitely noticed when shouldering the rifle.
IMG_20230103_114942.jpgIMG_20230103_115029.jpg
 
Gilly said:
First test carried out, I've not got a decibel meter so getting any semblance of "real" results is a bit difficult. In whichever case, it definitely does something! In a straight up test against an A&M twink it does sound a bit quieter, but at the same time it could just be a tonal change. Mine does seem to have a slightly higher pitch to it. I'll try and get a video. any who's here it it is!

Generally I think it looks pretty damn good with the glaring exception of the front cap, where the clear coat has gone all weird. I think I may have put too thick a layer on. only a 10 minute job to sand it back an re-apply so not an issue. It's 40mm diameter, 150mm in length and comes in at a featherweight 80g, the weight reduction is definitely noticed when shouldering the rifle.
View attachment 128731View attachment 128732
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Looks good, laptop and audacity will give you an idea about the noise level when compared to each other. If you have a 24bit soundcard and separate mic you can get rather good readings.
 
rkr said:
Looks good, laptop and audacity will give you an idea about the noise level when compared to each other. If you have a 24bit soundcard and separate mic you can get rather good readings.
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good shout. I've used audacity before for a different project, to be honest I completely forgot about it. not sure what soundcard I'm running and I'm pretty sure I no longer have any external mic's though 🥺. The other option was to use a decibel meter phone app, results would have to be taken with a large pinch of salt but it would potentially give an indication if there was an actual difference between the two. Will give it a go anyway and see what happens.

I've still got enough carbon left to have a play with some other designs. I'm thinking chamber, baffle, chamber, baffle, baffle for the next one.
 
Mikmee12 said:
Loving the 2AM. Looks fantastic. It never ceases to amaze me the level of skill that some of the guys on here have. Brilliant work 1260!
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Thank you Sir . was a solution to a problem 🙂👍 @Boysey has been near it when shooting . when weve had the 50 yard range to our selves which is in a old railway tunnel at the Ranges at Devizes.
 
rkr said:
Background noise varies as does settings of your measurement devices, gun settings etc. That's why I never look at absolute values but always start by measuring a set with the gun I use and Weihrauch silencer and then measuring whatever silencer or mod I'm testing. That way I always have a baseline that I can compare things against.
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I use the misses we were out at gone 2 in the morning testing . I shoot at a coke can by her . starting out at 40 yards then closing the range down . i know she carnt here the rifle going off coz the tin makes her jump 🤣😂🤣😂🤣
 
Wait, you aim for the can and missus jumps - is your scope OK? Unfortunately getting my missus to stand in the field while I shoot cans beside her is not going to happen (although I do like the idea). You could use a laptop instead of missus to get more reliable data.
 
rkr said:
Wait, you aim for the can and missus jumps - is your scope OK? Unfortunately getting my missus to stand in the field while I shoot cans beside her is not going to happen (although I do like the idea). You could use a laptop instead of missus to get more reliable data.
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I have night sights . she features in a lot of my testing . sometimes it her doing the shooting 😊 dont laugh . I trained her . she can take out a 5p at 50yards in the dark .

 
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