How to Foam Fill A Silencer for Airsoft for $0


Foam filling a silencer in airsoft is common practice, mostly it is used to make guns like polarstars extremely quiet. Here’s a quick guide on how easily foam fill a silencer. Okay so by $0, this is assuming you have the foam already anyways.

What You Will Need

foam fill step 1

We’re using a boba straw because we are cheapos, but if you have a spring laying around, this is what most people use.

Cut The Foam

foam fill step 3

Cut the foam block so that it fits nicely in the silencer. We lift it in square shape, you can round off the edges if you want to, honestly I don’t think it makes much of a difference. You want a nice snug fit, not too tight, but also not too loose otherwise it won’t sit in place and BBs could get stuck!

We just got our fancy new K Tech silencer in so that’s what we’re using for this tutorial.

Ram a Screwdriver Through It

foam fill step 4

Take a screwdriver or a pen and ram it though the foam block.

foam fill step 5

Make sure it goes all the way through.

Make The Hole Bigger

foam fill step 6

Try not to break the foam, but we used a scissor to make the hole bigger so that the straw (or spring) can fit nicely inside.

Stick the Straw (Or Spring) Through It

foam fill step 7

Put it through one time to make sure you can get a good fit. This is why we use the boba straw because the tip is sharp.

Cut The Straw (or Spring) to the Proper Length

foam fill step 8

This is self explanatory.

For those using Boba Straws, Cut Holes In It

foam fill step 9

The more holes you cut in it, the better, however we try not to ruin the integrity of the boba straw, it’s already a bit weak.

Put the Foam Inside

foam fill step 10

Now that you got the foam inside, put on the end cap and check if everything lines up.

foam fill step 11

There you have it, a basic foam filled silencer! Now this works well with polarstars. It probably isn’t going to do much for GBB pistols since most of the noise comes from the slide, but perhaps a GBBR could potentially work, or reduce the broadcast noise from a distance. However the best use for this is on a polarstar or even some AEGs.

Ways To Improve It


It may seem counter intuitive, but in the case of an airsoft silencer, using less foam can be more.

By removing some of the foam, we can create larger air pockets and chambers to allow the air to escape through. Now in theory this should make it quieter, and in practice on our Pstar we didn’t really hear much of a difference. But that won’t stop us from making it better, I’m sure on some other types of guns it might make an actual difference.

However, in this case, instead of using a boba straw, your best bet may very well be to use a spring.

Now truth be told, this is probably one of the ugliest foam inserts you have probably seen but this is a $0 tutorial for making a quick and dirty foam filled silencer! As long as it works, it works…

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