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Dan_W

Silent/Quiet AEG?

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Anyone know of a quiet AEG or how to make one quiet, I don't like to mess about with the internals much either so something quiet stock would be nice :)

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My realsword type 97b was very quiet. Something to do with the gearbox being buried in your shoulder inside a lot of plastic helped to keep it quiet. My ICS CXP whines like a banshee though, but always has.

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sometimes by putting a decent silencer on the end you decrease the sound levels by a fair bit, unless you have an AEG with pneumatic blowback meaning there's more then 1 way the noise from the gearbox gets out.

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foam.

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Some guys at my local have P90's which seem extremely quiet.

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sometimes by putting a decent silencer on the end you decrease the sound levels by a fair bit, unless you have an AEG with pneumatic blowback meaning there's more then 1 way the noise from the gearbox gets out.

 

Gearbox's are noisy no matter what all your doing is dampening the sound by giving it somewhere to echo Unless it's a Foam Filled Suppressor (No Such thing as a Silencer)

 

Some guys at my local have P90's which seem extremely quiet.

 

P90's are exquisitly quite the majority of the time because damn near enough of the thing is surrounded by our body's so just act in the same way as that fluffy stuff in suppressor's.

 

My realsword type 97b was very quiet. Something to do with the gearbox being buried in your shoulder inside a lot of plastic helped to keep it quiet. My ICS CXP whines like a banshee though, but always has.

 

Same as above as to the reason (They will sound loud to the user but they will be really quite to everyone else)

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How do you apply the foam, and what sort of foam. Would it not overheat or melt anything?

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You just have to pack it in around the gearbox, just stuff like packing foam, G&P AEGs come with it.

 

Surrounding the internals with it will probably be a massive ball ache though. You could fit a tightbore barrel and upgrade the hop unit, they're very easy upgrades that will increase range, then you might be able to hit people from beyond their audible range of you lol.

 

Thinking outside the box!

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A bit of audio engineer science: the foam inside an airsoft suppressor is, for most practical purposes, useless. This is because the individual cells within it are much smaller than the wavelength of the majority of the sound you want quietened. At most it will slightly reduce the high frequency content, but in the upper band that only kids, nuns* and recording gear really notice. You could get considerably more of this muffling effect by filling the suppressor body with Rockwool loft insulation, because it's much denser than foam, but it's horrible stuff. You'd want to fit some kind of mesh as a continuation of the barrel too, because Rockwool wouldn't hold its shape like foam. The only thing that foam in G&P AEG's can be doing is dampening mechanical transmission of energy, as a shock absorber, Ed, for the same reasons above. If you could fit thin layers of rubber between the gearbox and the AEG body, this would do the same thing more effectively.

 

The way that suppressors work is less about muffling and more about the phase of the sound as it travels through the suppressor. No, not Star Trek, but If I were to try to explain it thoroughly, I suspect there'd be more interest in beaming up. An easy way to imagine it is like water filling a bath. If you use a hand or something to stir it while you run the cold into the hot, you have to pay attention to make the water go round and round, right? Otherwise it goes back and forth in waves... OK, so if you keep pushing the water back and forth with the same rhythm, ie at the same frequency, the waves will get bigger and bigger until the water slops out of the bath, but if you dip your hand in between the wave peaks and paddle, you'll stop them, right? By doing that you are adding energy to the system 180° out of phase with the waves already there...

 

In a suppressor the chambers create pockets for the muzzle gasses to expand into and reflect a portion of the sound created by that rapid expansion along the path of the bullet/BB, but out of phase with the original. This means that a range of frequencies of sound are partially cancelled out, which not only reduces the overall sound pressure level in decibels, but also alters the timbre so what you hear has a different quality to the original, as a tuba sounds different to an electric guitar. The idea is that if, say, an orchestra were told to expect trouble when they hear an electric guitar, if they hear a tuba they don't worry about it.

 

Personally I've never taken an airsoft suppressor apart, so I don't know if they use multiple chambers. I imagine that the cheaper ones probably don't, but one thing which would help is if they are different lengths, because then their effect would be spread over a wider frequency band. The trouble is that a lot of the sound of an AEG isn't coming out of the barrel at all, but rather straight through the sides of the receiver. As I said above, a shock absorber between the gearbox and body would help, but I've yet to find an AEG with enough space to fit anything in there.

 

As for quiet guns, Tokyo Marui are reputed to be very quiet, but I can only vouch for their M14, which is amongst the quietest I've ever heard.

 

*It's a sad fact that women's hearing lasts longer than men's naturally, independent of environmental factors, so cloistered women whose hearing doesn't get damaged by loud sounds will make good airsofters :)

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In that case I might ask the local nunnery if they would like to join my airsoft team :P. So in short fake suppressors are useless and the best way to quieten it is to pack some rubber into it? Would your CYMA AK have much room in it Ian? Thanks for that info, as mine is apart at the minute trying to sort out the fiddly trigger mechanism I will see if there is much room in it to dampen the sound a bit. Mine is a lot louder than my friends, it has a proper bang to it and we ave the same make, that's probably what led to the cylinder head breaking. :(

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No, my CYMA AK is so tight around the gearbox that it can be a bit of a bugger to get the thing back in and seated horizontally. I dab a bit of grease on the inside of the receiver. It's plastic though, so I expect that if I stuck some really thin rubber sheet to the inside of the receiver, with a good dollop of grease it would probably fit, but that would make the battery tray assembly even more difficult to seat with those poxy little angular hook-thingies in place properly. I dare say that the design works a treat made from a decent metal, but made from plastic it's an arsewank waiting to happen...

 

No, I don't know that all airsoft suppressors are completely useless, just that the foam inside them is the next thing to it. Even a single chamber suppressor will have some antiphase subtraction effect. Something that the foam would work at though is to hold some washers in place to make chambers inside a suppressor.

 

If you could find some washers big enough around the circumference to fit closely to the interior circumference of the suppressor, with a hole say 8mm in diameter (unless the washers jam tightly against the interior (in which case no foam will be needed), they will slip down so that even a 7mm hole might not be big enough for a BB to pass through without clipping the washer), you could cut the foam into say 4 unequal lengths and fit 3 washers between them. The thing is that internal chambers which aren't completely sealed would have less effect than sealed. Without testing I couldn't really guess, but the difference could be so much as to make doing it pointless unless you could make sealed chambers inside.

 

If you've had a busted cylinder head I'd guess that something was pretty drastically wrong inside the gearbox, but the absolute best thing you could do to quieten an AEG is cushion the impact between the piston head and the cylinder head, so if you've got it apart perhaps that's something to think about? Is it an AK? I ask because Element make what they call a 'Silent' piston/cylinder head combo, but as far as I know it's only available for version 2 gearboxes.

 

Something I have tried is fitting a rubber washer to the inside of the cylinder head, but it didn't do much. I think the rubber may be either too dense, so the energy is passing through it as well as it would through the plastic cylinder head, or not dense enough so that, because it doesn't reach right to the edge of the interior circumference of the cylinder, it's squashing so easily that the edge of the piston head is connecting with the corresponding position on the cylinder head pretty much unimpeded. Doing this did alter where the piston comes to rest however and I think it may have something to do with a recurring problem I've had with teeth coming off the sector gear... (but maybe not, because where the teeth come off isn't from the part in contact with the piston teeth).

 

I've just bought an airbraked piston head to make my AK quieter though. Ed has one in his L85 and it is nice and quiet - Lees Precision Engineering

Haven't got round to fitting it yet, but I have high hopes :)

 

PS - if you're having trouble getting the trigger back into a version 3 gearbox, I do it by assembling the gearbox without the trigger and that little slotted swivel-thingy. Then, holding the part containing the gears together as tightly as I can whilst cracking the front part of the box apart, I push the trigger in so that the left hand side pin goes into its hole. Doing that then allows me to pivot the trigger forward trapping the spring against the gearbox shell. Then that swivel-thingy left hand side pin has to get inside the box which means that the rear of the gearbox has to come apart a fraction more. In 1 smooth motion use a trigger pulling motion whilst simultaneously rocking the trigger up towards you (the right hand side of the gearbox) and the swivel-thingy pins and remaining trigger pin will drop into their holes without allowing the spring end to ping out...

 

:P practice mate :) I also use a thin sliver of steel to help hold the gears in position when I first close the 2 halves of the shell - it makes the job work 1st time more often than without it, but I'd say I'm an expert ver 3 dis/assembler and I wouldn't bet much on my ability to get it right 1st time - that 'kin trigger spring has a mind of its own sometimes it seems. Another trick is to use a good blob of grease to hold the spring in place so that it doesn't fall off the trigger pin as you bring it up against the gearbox.

 

Gearbox sliver-tool:

imag0941.jpg

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Ian have you tried Sorbo? Or is an air break better? I'm guessing it seals the nozzle in the cylinder head retaining a quantity of air which produces a cushioning effect so the piston doesn't slap against the cylinder head.

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Could you do a video on putting the trigger back in, or even better come to N.I. And do it for me?

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Ian have you tried Sorbo? Or is an air break better? I'm guessing it seals the nozzle in the cylinder head retaining a quantity of air which produces a cushioning effect so the piston doesn't slap against the cylinder head.

Don't know what Sorbo is?

 

Yeah, the airbrake piston head has a small prong that sticks out of the centre so it goes inside the tube of the cylinder head. They come in acetal or aluminium. I got the ally one - I'm guessing that the prong can't make anything like a seal against the inside of the tube, without any rubber or soft plastic coating, but yeah you've got the right idea in principle. Even if it just drastically reduces the speed at which that last bit of air can escape the cylinder, then it will compress as a cushion..

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Could you do a video on putting the trigger back in, or even better come to N.I. And do it for me?

lol

 

I don't have a camera, but my phone has a stupid amount of memory so maybe I can prop it in position to video me doing it - big lump of blu tac might do it!

 

I'm not going to promise though, cos although I really ought to have got on with sorting Sabine out yonks ago, I'm having emotional issues with her...

 

Edit to add: having thought about it some more, I'm pretty sure that you wouldn't be able to see anything useful unless I could mount my phone to my face.

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Sorbo pads are similar to rubber washers but softer, some come in pairs, a doughnut shape for the cylinder head and a solid one for the piston. Idea being that they dampen the impact of the piston. Got to find out what gearbox parts can fit in the ICS L85, V2 or V3, I can feel another question for Ed. At £12 for an air break piston from LPE it looks like it could be worth giving it a go.

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Yeah, that's what I thought: the theory seems sound (as it were lol) and for £12 well worth checking out.

 

L85's don't have either ver 2 or 3 gearboxes. I think it's ver 6 but whatever it is, it's sort of like an M14 box, but not interchangeable.

 

But yeah, the ICS L85 does take the LPE airbrake piston head - Ed has one - it was him that put me onto the idea.

 

re Sorbo pads then, doesn't the piston head one block the vents that allow the piston to move back more easily?

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I was looking into them but had wondered about that, some people seemed to be talking about it being pairs, the one on the piston head looked smaller so maybe it only goes on the middle, leaving the holes uncovered. Cheers for the info, I'll maybe message Ed to find out which one he bought. I know its something odd but ICS aren't much help about giving out that info.

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I always assumed the sorbo pads got stuck onto the cylinder head, so the piston head is free to act as it otherwise would, but gets cushioned when it hits the cylinder head.

 

I imagine combining a sorbo pad or two with the air brake piston head would provide some pretty über silenced-ness. Stick a silencer on the front too (not you Nick, L85s can't have suppressors - it's illegal!) and I bet you'd have a pretty soundless gun.

 

I've got the aluminium LPE piston head, btw. I didn't even realise he made an acetal one. I'd be worried it might destroy itself spectacularly if you got the AoE wrong.

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Hmmm... so, Ed, I was just thinking about your airbrake piston head and Sorbo pad combo idea. It occurred to me that the airbrake would start working earlier in the stroke cycle, as the prong enters the hole in the pad, not the head tube. Which lead me to wonder just how soft the pads are, because if the air compression squashed the pad to any significant degree, the inner edges of the hole in it may press against the airbrake prong. This would probably dramatically increase the seal between the brake and cylinder tube. I seriously doubt it would affect FPS, unless the cylinder is one of those with vents in the side quite far down towards the front, because that last bit of air would still be expanding inside the barrel long (in relative terms) after the BB had exited the muzzle, but how likely is it that the seal would be good enough to stop that last bit of air completely?

 

Not very, eh? Which lead me on to wondering about the operation of the airbrake normally also. What is your air nozzle on your L85 made from, Ed? Have you ever tried closing off a bike pump with your fingertip and pumping it? It gets really hot almost as soon as air forces out......

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I don't think the pads would cause the prong to seal any sooner, I doubt they'd even be the right size to perfectly cover the cylinder head, they're literally just there for a cushion effect, they could be O-rings and have the same effect.

 

I don't think any heat generated would be that much of an issue. The worst I can see happening is the heat potentially baking the sorbo to make it really hard, with the effect being the piston would stop hard, as it would without the sorbo, except by the thickness of the sorbo, sooner. If the sorbo didn't bake hard in the heat, then I think it'd work really well.

 

But I personally think AEGs sound better when they're loud, the piston and cylinder head slapping together, combined with the excess air escaping the barrel make a really satisfying "thump" sound and of course loudness is more true of reality, the gearbox whines are also hidden better.

Though, in real life the target would die in most cases before they heard the crack of the rifle, so by making an AEG super quiet, you could argue that was just as true to real life, just for opposing reasons.

 

That said, I'll take g'box longevity and reliability over the noise it makes any day, because when you're in the heat of it, all that matters is getting rounds on target and any thoughts you have about disliking the noise just go right out of the window. It's the same theory I used to assure myself it wasn't a big issue going for plastic STANAG mids before I started using Emags lol.

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Don't worry Ed, I totally agree silencers on L85’s are just plain wrong! But I’m looking for ways to reduce the smack just a little and improve the efficiency. I want to spend a bit of time really making sure it is working just as good as I can get it.

 

What gearbox parts have you used in your L85 as that’s my next area to work on, is it the V2/V3 cylinder head and piston head from LPE you fitted? I know the piston is odd but I’m not sure about the other bits and pieces.

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This is the one I've got: http://www.leesprecision.co.uk/cnc-machined-v2-v3-aluminium-airbrake-piston-head.html

 

I'm still unsure about what the compatibility for the other parts is like, I've no idea whether they're generally V2 or 3 etc, but the one I've just linked definitely fits and it makes quite a substantial volume difference.

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You're probably right, Ed. I just had a close look at my new airbrake head and tested it up against a spare cylinder head: it doesn't actually fit that tightly at all. I've heard yours so I'm still optimistic, but if I hadn't, right now I'd be pretty sure I'd wasted my money lol!

 

Has anyone here tried Sorbo pads? Probably have to start a new thread to get an answer to that, but we shall see...

 

I don't think suppressors and L85's are completely mutually exclusive. Yeah, some poxy 120mm fake trades bollox would be horrendous, but then again they're pretty bad on anything. Well, on an M4 they look right @home of course, but that's just because M4's are bollox. I think a 30mm diameter 200-ish mm entire barrel replacement from inside a RIS would be ok, especially if it was sprayed to match rail ladders & furniture.

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