Supressor filling

[xtylertyx]

I am making a supressor for a NBB gun that i'm running on propane and was wondering what is a good filling to muffle the report. I figured I would post it here cuz it doesnt really fit into any of the other forums.

[Styrak]

Foam. Or foam-ish like material with lots of holes/airspace.

[arman]

here i just took a pic of the inside of my supressor its soft foam

[arcanuck]

Depending on how well you want it to work, the filling to use will depend on the sound absorbent material's NRC and what frequencies you want to remove. The suppressor's internal volume will be a major deciding factor in how much can be used and also in determining the volume's Fs (resonant frequency) and second high order Fs. The suppressor will also amplify these sounds and can defeat the purpose, partial reason to why most are not super effective.

[L473ncy]

Cough cough. Manufacturing certain devices....

[CDN_Stalker]

Originally Posted by arcanuck

Depending on how well you want it to work, the filling to use will depend on the sound absorbent material's NRC and what frequencies you want to remove. The suppressor's internal volume will be a major deciding factor in how much can be used and also in determining the volume's Fs (resonant frequency) and second high order Fs, the suppressor will also amplify these sounds and can defeat the purpose.

Wanker nerd. Lol.

Do what I do, get copper pipe foam insulation from a hardware store, cut into 1/2" slices, then take half of them and cut the thickness down to 1/4" or so. Alternate the slices, thick and thin, this creates foam baffles within the suppressor. Cut each to the right size to fit snugly (after expanded) into the tube, and use a barrel or a rod to press all into the outer shell of the suppressor. Literally what you want is vertical surfaces for the gas and the report to hit, isn't so much just open cell foam to absorb it, you need to have obstructions.

[arcanuck]

Originally Posted by CDN_Stalker

Wanker nerd. Lol.

Do what I do, get copper pipe foam insulation from a hardware store, cut into 1/2" slices, then take half of them and cut the thickness down to 1/4" or so. Alternate the slices, thick and thin, this creates foam baffles within the suppressor. Cut each to the right size to fit snugly (after expanded) into the tube, and use a barrel or a rod to press all into the outer shell of the suppressor. Literally what you want is vertical surfaces for the gas and the report to hit, isn't so much just open cell foam to absorb it, you need to have obstructions.

Actually there are a couple real reasons for using solid baffles, one is to create a series of chambers with high enough resonating frequencies that the damping material can absorb or otherwise nullify this acoustic energy and convert it to heat over the relevant bandwidth. The size of these chambers has to be tailored to the projectile bore diameter and barrel length, rather than having sound bouncing around randomly in these aforementioned chambers. The second is to form a seal as good as practical, forcing the expanding gasses to fill the cavities and in turn lower the pressure present at the muzzle; most suppressors will have a preliminary chamber to aid in this. Though it will not matter in Airsoft, it also relieves some of the pressure from the baffles to extend service life.

Again the lack of design knowledge and how to implement it properly keeps individuals from being successful in adequate attenuation, but that is a good thing I suppose since we don't want people building real ones either. So I guess if someone wants to change the sound and maybe lower the report a bit, foam will work.

[xtylertyx]

Should I pack the filling tight? Or leave it loose with extra airspace? Or fill up all the space, without squishing anything?
thanks

[CDN_Stalker]

Tight enough to stay in place and not shift, loose enough to not have it get pressed into the BB's path.

Originally Posted by arcanuck

Actually there are a couple real reasons for using solid baffles, one is to create a series of chambers with high enough resonating frequencies that the damping material can absorb or otherwise nullify this acoustic energy and convert it to heat over the relevant bandwidth. The size of these chambers has to be tailored to the projectile bore diameter and barrel length, rather than having sound bouncing around randomly in these aforementioned chambers. The second is to form a seal as good as practical, forcing the expanding gasses to fill the cavities and in turn lower the pressure present at the muzzle; most suppressors will have a preliminary chamber to aid in this. Though it will not matter in Airsoft, it also relieves some of the pressure from the baffles to extend service life.

Again the lack of design knowledge and how to implement it properly keeps individuals from being successful in adequate attenuation, but that is a good thing I suppose since we don't want people building real ones either. So I guess if someone wants to change the sound and maybe lower the report a bit, foam will work.

That's a bit much, comparing airsoft suppressors to the real steel ones. Lol, show off.

[FOX_111]

Originally Posted by L473ncy

Cough cough. Manufacturing certain devices....

cough cough... not real steel... cough... would by silly to try for real steel... cough...

I'm off getting cough sirup.

[m102404]

3M scrub pads