I don’t know if this would work for airsoft, but I have a suppressor that is purely a carbon sleeve on a barrel.
Originally it had a more traditional suppressor as an outter tube with baffling.
The underlying barrel has more than the normal amount of porting so it would vent well into the baffling. So I had a heavily ported barrel for maximum airflow, and a slip on tube lined with green scourer material. After I dropped it a few times I finally lost it, and with some attempts to unsuccessfully recreate it (presumably without the right mix of materials and tolerances) I asked the guy to make me a new one. He was then testing out carbon fibre alternates.
The original was very quiet but the upgrade beats it.
With a close fit of the carbon fibre there seems to be just enough space for the air to disperse and the carbon absorbs vibration.
Like many things there’s the fun factor of which includes just having look a like parts. So effectiveness of a suppressor isn’t everything.
If you’re after noise reduction (or just changing the sound) then a functional suppressor will work upon barrel exit only with the rest being down to the guns action.
