Everything I know or have found out about quieting a mechbox
WARNING: This post is going to end up being pretty long for a forum post.
The big idea is that sound comes from 2 places in an AEG, but is caused by 4 different things, we'll take them one by one. The two major places that cause noise are the mechbox and the tip of the barrel. Is there a type of gun more suited to being suppressed than another? Yes, the two most commonly mentioned are the p90 and the AUG (not so Augly NOW, is it?!), heads up, links coming your way!
1. Quest for the Ultimate AEG - AirsoftForum.com
2. Northeastern Airsoft Group - NEASG - Quiet AEG??
3. ArniesAirsoft: FIRST Factory Shadow AUG
4. Sacramento Airsoft :: Californias Airsoft Leaders - How do I make my AEG quiet
5. Airsoft Mechanics - Quiet Gun Project
Why are these two AEGs the most popular when it comes to making a quieter gun? These two have a lot of room around the mechbox with which to stuff foam or some other acoustic material (Dynamat, Auralex acoustic foam, seat upholstery, you name it, somebody's tried it.).
6. Airsoft Pacific - What type of foam works best for quieting an AEG?
From what I understand, materials like dynamat help quiet high frequency noises, whereas foam tackles the low frequency. I might have that backwards, so don't quote me on it.
SO, we'll tackle the easiest problem first. When the BB leaves the barrel, or just air for that matter, it makes a pop noise. If you think about it, your barrel is really just an uninterrupted cylinder of air coming right from that oh-so-noisy piston head. The only real solution to this is a foamed suppressor, there are plenty of arguments on both sides of the "do they really work" argument. After owning a TM mk23 Socom non-blowback gas pistol for a little under a year, I'm definitively on the "yes they do work" side of things. Yes, I know, gas gun =! aeg, but it's a proof of concept, on this non-blowback, the noise comes almost exclusively from the end of the barrel, and the difference between having the foamed silencer on and off is staggering.
7. self made silencer - Airsoft Canada
8. Custom Silencer - Airsoft Canada
9. Silencer - c3airsoft
As you'll see in link 8, it's possible to make your own silencer, maybe we could get Tiger Stripe to type up a guide to how he made up his pvc one?
The next noisemaker is the motor.
10. Who has created their own silent piston? - Airsoft Canada
There are claims that the two quietest motors available are the EG700 and the EG1000, the latter of which comes standard in the Tokyo Marui P90. You can also adjust the motor height, generally with an allen key on the bottom of the motor housing. I've read to adjust it the best method is to just do a "is this better or worse" after a quarter turn.
Next come the gears.
There are two ways to fix this one up, and both of them sound easy, but aren't quite as easy as they sound. The first, and most important way, is proper shimming. Shims are cheap, generally around 2-4 bucks, and come with an assortment of different shim sizes. There are images floating all over the web that say "Oh, just put a .05 shim here and a .03 shim here if you use an m4." I'm not sure just what to think to think here, since I don't have an m4, here is the method I've been using, seems to work alright:
11. 858airsoft.com - How to shim an AEG version 2 Mech box
I'm no expert on AEG shimming, it's supposedly one of those things that just comes with experience, so maybe some of the vets have some good shimming tips for us. The other solution is helical gears, which are reportedly much quieter than flat gears by default, but a "perfectly" shimmed set of flat gears is allegedly able to rival a helical set. The reason that they are quieter and better for your mechbox in general is that they have more teeth in contact at any given time, and therefore a good shimming job is more important on helicals than on flats. If you're asking yourself "If they're so good, why don't ALL AEG's use them?" here is your answer:
12. Systema Gear Sets - Flat Gear Sets - US$53.50
13. Systema Gear Sets - Helical Gear Sets - US$88.20
They're more money!
The last and most disputed noisy part is the piston head contacting the cylinder head. The least headache inducing solution are the silent piston head sets, but the catch is that if you're using a p90, you aren't able to use the silent piston sets. The reason for this is because the hole the air exits through (in the cylinder head) isn't centrally located, it's offset, as seen in the first picture on this link.
14. AirBrake Tech
That's one of the most linked-to sites on forums whenever anybody asks about quieting an AEG, so it's worth a look.
15. AirsoftMechanics.com - Mini-Review |: Systema Silent Piston and Cylinder Head
16. Silent Piston sets - Are they really quieter?
17. Angel Silent Set
The other solution is an airbrake, which utilizes a padded cylinder head and a plunger on the piston head. Link 13 is the most popular link with regards to airbrakes. Here are three more links from a translated page. At the very bottom of the page are actual sound clips of the products in action so you can compare for yourself! If there is anybody who can translate these pages better, please let me know, because it seems like some of the most important parts are untranslated or mistranslated.
18. Gungineer 01 - Making an Airbrake
19. Gungineer 02 - Making a padded cylinder head
18. Gungineer 03 - The results
Yours truly is also giving this airbrake business a go, here's the thread:
20. Stripped screws - c3airsoft
And after a super long post and 20 links later, that is about everything I know on making an AEG quieter. Hope that I managed to help out somebody, and if you learn something new or actually achieve a pretty quiet AEG, let me know, I'd love to hear about it!
