The Principle

Suppressors reduce the sound of the explosion by trapping and slowing down excess gases. With airsoft silencers, the most important thing is to reduce the high frequencies, because they are the main culprit for revealing the direction of the sound source. It is always easier to locate a crisp “bang” than a dull “pop” deprived of high harmonics.

Therefore there is a complex of chambers inside a suppressor, that trap and slow down the gases. With real ammo, the gases are burning hot, so the chambers must be made of steel baffles. As far as airsoft silencers are concerned, many experiment with different chamber shapes, but realistically - a simple sponge has proven to be the best! As long as it be an open-cell sponge, i.e. one that absorbs water - and not a closed-cell one, because air cannot enter or leave them, gaining poor effect on suppressing the sound.

The Idea

I came up with the idea to make 3D printed "spongy" disc inserts instead of using an actual sponge (which I don't always have at hand, and is hard to cut neatly without a laser). Although made of rigid plastic, their thin spirally arranged threads will trap the air in the same way as a regular sponge. With 3D printed inserts, the external and internal dimensions can be accurately determined, so the result will be much neater - and the central spring, which is usually placed to prevent the sponge from slipping in the way of the BB - will no longer be needed. Furthermore, that way we can easily make different discs with alternating inner hole sizes, that when stacked alternately, which further slow down the air.

How To

1. Make 5mm* thick discs, with an outer diameter that is approximately 0.1mm* smaller than the inner diameter of your suppressor, so that they can easily slide in and out without rattling. First make and try just one before printing the rest!
2. A hole should be left in the middle of each disk, where the BBs will pass. You should make two variants: one with a 10-11 mm center hole, and the other with an 18mm* hole .
3. Discs should be printed without outer perimeters and without top and bottom layers, using the Gyroid infill with a density of 30%*.

PETG or PLA will work great, but if you have a good dialed-in profile that does not produce much stringing, perhaps TPU could be the best choice - even though I couldn't hear the difference between a real sponge (which is the best option) and the PLA printed ones. I found the difference in price when using TPU not justifying its just marginally better effect.

The discs should be stacked alternately in the muffler. I usually first print a sleeve with 1mm thick sides, in which I then stack the discs. That way I can easily take them in and out, without having them scattered around.

(*) All the numeric values stated here have proven to work fine for me, but feel free to experiment and find out which works the best for you. You should keep in mind that reducing the inner hole below a diameter of 10 mm will improve the performance, but will also significantly increase the chance of ball hitting the baffle.

Modelling the discs

There are several ways you can model the discs:

• Directly in PrusaSlicer using Add Shape for the disc and Add Negative Volume to making the hole in the disc. That way you can easily play and experiment with various sizes ("Sponge Silencer Baffle - Cylinders.3mf")
• Using a CAD of your choice and then slicing the model in your favorite slicer, with the previously described settings.

Caveats

Using too dense infill will decrease the sound efficiency, as it decreases the volume of the cambers where the sound travels.

I found the 30% gyroid infill to have the best effect in my case, but the mileage may vary.

Instead of just increasing the gyroid infill you might also try decreasing extrusion width from 0.45 to 0.4 or even lower. It will make the “sponge” finer and more efficient, but more brittle.

The Attached Example

The attached files are examples for inserts used in my replica of a KAC QD Suppressor. The suppressor itself is not included here! The discs are 5mm thick, outer diameter is 29.4mm and inner diameters are 11mm and 18mm. 

They are meant to be stack in the insert/adapter tube (Baffle Adapter), also tailored for my suppressor, but you can make a similar one matching your specific needs.

Similar Tips

For further reading on airsoft tips and stuff you can follow my Facebook blog. It is in Croatian, but auto-translate does a pretty good job (aside some occasional quirks).

Legal Disclaimer

Check the laws of your country to verify the legality of suppressing the sound of airsoft replicas. If your laws don't allow it, you should not be using this!

See Also

My other suppressor models are available here:

• KAC QD Suppressor Replica
• Surefire SOCOM 556 RC2 and RC Suppressor Replicas
• Surefire SOCOM 556 RC3 Suppressor Replica
• Surefire SOCOM 762 RC2 and RC Suppressor Replicas