Silencer/Supressor

[Sewdhull]

I know these are used cosmetically but has anyone used these to reduce or mask noise in Airsoft?

How effective are they? Anyone do anything in particular to make them effective?

I'm aware that there's significant noise from an aeg gearbox or gbb slide or bolt which will be unaffected.

I'm also aware that cylinder to barrel ratios matter in this respect as does the amount of piston slap in the cylinder, so the amount of noise generated varies from gun to gun.

I've seen some threads in other forums from way back when, but I wonder if we've moved on in any way.

 

[The_Lord_Poncho]

Most effective in gas guns for the reasons you mention, where they do a very good job of reducing noise. I did add foam to the two foot long supressor that came with the SR25 (AEG) which isnt a mega load AEG in comparison to some. I think it's made a slight reduction.

 

[Tackle]

Can't say for all, but I remember one of my g36's was definitely quieter when using a suppressor. 

 

[JimFromHorsham]

Gas , HPA , NBB , springers they do make a difference , volume with a soft filling is best ime . 
 

AEG , not so much .

 

[GiantKiwi]

Baffles do exist if you have access to a 3d printer, but they only seem to be noticeable in difference on things either HPA engine or spring based. Better off with foam overall though.

 

[Sewdhull]

Cool, I'm slowly putting my sd6 together, it's silencer has foam already, I'll have a play when it's firing again.

 

[Impulse]

They don't make too much difference with GBBs and AEGs, but they make more of a difference than you realise. With GBBs you have the sound of the slide if pistol or the bolt if rifle going back and forth and with AEGs you have the sound of the gearbox, however in both cases a foam-filled suppressor will dull the popping sound as the air or gas escapes the inner barrel. This is more pronounced in gas guns than AEGs, but it happens in both. Also, the gearbox noise and action of the gas blowback are near your head, so you hear them more, however your muzzle will be, or at least it should be, pointed towards the enemy. I did some testing with a friend where I walked down the range to hear what guns sounded like from the other end, and you'd be surprised what a difference muffling that popping sound makes even in AEGs and GBBs.

With spring it helps, but you still have the noise of the piston slamming forward.

However, gas non-blowbacks and HPA guns will love having a suppressor on them, as that popping sound of the gas or air expanding as it leaves the barrel is most of the noise and it's heavily muffled with a good suppressor. I've had people standing about 10m in front of me and not hearing a single shot with my m40 and m700 because they're suppressed and the only noise is a faint click of the hammer. Same thing with HPA, there's no real noise to speak of outside of the air expanding as it leaves the barrel.

 

[Pseudotectonic]

AEG has several sources of sound: motor and gearbox sounds, piston sound, and muzzle pops

• Motor and gearbox sound is mostly generated by meshing of gears and all the little mechanisms rattling, which can be minimised from source with shimming and tuning the overall rigidity of the system. Normally this is transmitted via resonance or reverberations through the gearbox and AEG body itself, so if you can dampen this vibration around the receiver area this can be reduced.
  

• Piston sound is a loud pop from the piston hitting the cylinder head. Similarly this can be dampened however you want with piston head + piston head combos/trickery, or something done to the cylinder or gearbox or receiver to dampen the vibration and transmission.
  

• Muzzle pop is probably not as loud as the above, but first you want to contain the expanding volume of air, and secondly dampen the vibration from being transmitted via the smooth cylinder shape of the suppressor.
  

These are all essentially sound insulation problem and there are several principles for dealing with this. Sound travels through air so any unnecessary air gap can be sealed to contain sound, but this is perhaps not practical for an AEG. Mass absorbs sound, so in theory filling your receiver and suppressor with concrete would be best but obviously this is not practical. Another way is material science, make it less resonant so it absorbs the vibration (i.e. sound) instead of transmitting it into the air, usually this means a suitably soft material, or even better, a composite material like applying 3M 2552 Damping Foil Tape so the vibration is turned into heat rather than being allowed to vibrate freely thus transmitting into the air.

Foam does not do much because while it slows the expanding air, it does not really dampen much vibration of the aluminium can that is holding it.

So in theory perhaps the best airsoft suppressor will firstly have damping foil applied to interior (to deaden the can body), and then layers of heavy weight acoustic rubber floor matting (the type used for soundproofing floors, use heaviest grade you can find), then the inner most post leave just enough diameter for some baffles (material doesn't matter) to allow the air to expand and be slowed before it travels towards the end of the can, you only need maybe about the same volume of the gearbox cylinder or even less.

Then if you put some damping foil on (inside) the receiver and gearbox and cylinder(I have some on my motor) then it will be even quieter, if you are going for ultimate stealth SD6 build.

Somewhat relevant video https://www.youtube.com/watch?v=SK9qpGqBBmg you don't need a whole lot to be effective.

Only downside is the 3M stuff is expensive and I am still looking for alternatives. This is not normal aluminium foil tape because this stuff has 0.254 mm thick aluminium (~250 micron) as opposed to the 30 to 50 micron thick common stuff, and you can't just double up the normal stuff because it doesn't work that way.

 

[Sewdhull]

Thanks for the replies and info.

As I see it there's two silencer type sound issues, the sound wave coming down the barrel from the piston hitting the cylinder head and the  'pop' from the escaping air at pressure after the BB exits the barrel.

Foam might deal with them both.

ALtho I rather think the sound might overtake the air moving down the barrel unless the BB exits before the piston slaps that cylinders ass.

Ive probably got enough to think about, don't want nerdish overload.

Altho I have used silent coat on my car before...

 

[Pseudotectonic]

Btw the inner barrel can be stabilised (centered) to the outer barrel if you wrap some tape around it which helps to reduce the barrel rattling and reduce any vibration from travelling along the brass

I do it at two points, one towards the front tip and one towards the back near the hop unit, with only two points you won't be applying bending force to the inner barrel if there is any knocks or bending of the outer barrel, because you need a third point to bend a straight object

 

[Adolf Hamster]

Gas , HPA , NBB , springers they do make a difference , volume with a soft filling is best ime . 
 

AEG , not so much .

This, a hpa with a big can on it is practically silent