In the real suppressor world pretty much all of the DB numbers are lies, and are taken in different environments on different guns with different calibers, bullets, barrel lengths, test methods, test machines, averaged vs cherry picked, and different people exaggerating the numbers. This leads to buys/owners saying that sound doesn't matter, which is dumb imo as there's no other reason I'd spend $200 tax, half a year of waiting, and up to 2K on a suppressor.
For airsoft we don't really advertise DB numbers, which is good as there's lots of different guns, power sources, powers, and all the other stuff I mentioned. The only reasons to have a can in airsoft are to cover an inner barrel, look cool, and of course make your gun quiet. No arguments for flash or whatever people say about real suppressors. Our sound sources are a lot different than firearms as we are dealing with cold air, or cold heavy gasses like propane and CO2. Real cans do a lot of silencing through rapidly cooling down a high volume of hot combustible gas, and less so on actually trapping gasses as that is near impossible except in weaker stuff like .22LR, 9mm, .32ACP, and similar things with less excess gas behind them. Since we are dealing with much lower volumes of gas at much lower pressures at way way cooler temperatures, we can get more creative and cheap with our materials and designs, which is pretty convenient.
I have experimented with a ton of different open cell foams, a few different Scotch Brite type things, decent amount of baffle materials, hull lengths and diameters, hull materials and wall thicknesses, hull coatings and wraps, end cap styles, and cap covers and coatings, end cap diameters, internal structures, and pretty much everything you can think of.
The best things I've found are
- Calmflex F2 foam
- Tight holes in baffles/foam and end caps
- Thick walled hulls
- Anti vibratory materials for the hull end caps, and hard pieces. Thick aluminum helps, but copper, lead, or brass would be ideal.
- Anti vibratory wraps or coatings like rubberized paint, powder coat, or various cloth tape. Dynamat Xtreme and similar things are probably the best, but they do add weight, and need a protective tape or sleeve on top of them. Another thing may be layers of heat shrink, both to cover a sheet of rubber or Dynamat, or as a anti vibe layer itself.
- 2 stage designs with "breaker" hard baffle stacks or cores in the start of the can to disrupt and significantly slow gas and sound, making it easier for foam or similar materials to absorb.
- Air stripper type things in end caps and the beginning of suppressors to shave away and redirect sound and gas. You can look up "airgun air stripper" and look at what they look like, they are a little like a muzzle brake or compensator but more for accuracy than recoil management. They are mainly used for competition airguns, but could likely be applied to airsoft for both accuracy and suppressors.
- No flat baffles. You want reverse cone shaped stuff that will "shave" air away instead of just have air smash into it. it's good to try and direct that gas in a way where it will crash into oncoming or leaving gas and slow the other gas down, as this is what the best suppressors seem to do. Also a good idea to add as much surface area as possible to surfaces seeing a direct blast, with things such a coatings, rough textures, or 3D printed/machined designs. Real steel 3D printed suppressors are becoming very advanced due to the design and manufacturing freedom that comes with 3D printing.
- Hull length and diameter. Longer is better, but fatter isn't. 29-35mm is about the perfect diameter from my findings, and very similar to what airgun people prefer for calibers .177-.25.
The reason we see a lack of this is because it isn't really a priority to companies, and will probably be a bitch to ship to the USA. The cans may likely would not work well as there isn't a lot of crossover with designs and all that, but it would likely not happen here nonetheless. DonnyFL airgun suppressors seem to have done well here, but the ATF isn't exactly fair and I would not expect any success for a good airsoft can. We are alright with our foam stuff as it is sort of a grey area, but I wouldn't push my luck. Also the lack of ease of use when it comes to the average airsofter, as on the whole, we are pretty damn stupid. Tighter holes are better for sound suppression, but along with trapping gas and sound they will also trap BBs if your gun or parts are not well centered or whatever, you run shitty BBs, or any number of things. Airsofters are barely able to wrap Teflon tape on their barrels to stabilize them, so I doubt they could be trusted with any suppressor with a hole smaller than 15mm lmao.
I don't really get into measuring sound stuff as it's expensive, variable, and I don't care to learn a ton about it, so I just rate everything by ear as that's the main thing I'm trying to achieve, something a human ear has a hard time reading. It's good to test sound from different distances, as sometimes a gun will be quieter when you are shooting it than than when you are in front of it, and sometimes the other way around. It's good to test front and sides as shooters position doesn't matter for our needs. Test environment is also important, as a forest with lots of leaves/needles and vegetation will be much quieter than a mowed field or bare forest like how mine is during the fall, winter, and spring.
There is also sound type or pitch, as although a quiet high pitch noise will seem quiet, but at range it may be louder seeming than a lower and louder noise. High pitched sounds travel further, and they are usually more attention grabbing to a human ear. This is why the MK23 does so well even though it is relatively loud compared to my M4 or old sniper, it has a very low pitch. There is also sound duration, which is something to consider. The longer a sound happens or the more times it happens, the easier it is to hear and then even track it's location. I use this to my advantage when stalking and murking AEG players as an AEG takes a long time to cycle, and most need multiple shots or even full auto to make a hit. The shorter and less frequent a sound is, the better. This is why the Wolverine BOLT is so good, as it shoots without venting any air elsewhere, and fires instantly. Other HPA engines that need to cycle a nozzle will be louder due to the time it takes them to cycle and fire, especially open bolt ones, but higher PSI and lower poppet and nozzles dwells will remedy this and speed things up.
Lots of writing, but a good use of a lunch break.