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Alstone · Moderator & Site Supporter

Hi Bob
Which one do you mean, the converted AA, or the short homemade one, I can strip out the AA one so you can see whats inside but as for the short unit these are sealed. I never think to take a photo when I am making them, any way I will strip out the AA one as this unscrews, and give you some idea whats inside.

Al

BBGun Bob · Veteran Member

I seen the pics of the AA you took apart I would like to see the smaller more efficient one you made.

Thanks
Bob

Alstone · Moderator & Site Supporter

Bob I’ve taken the insides out of an unfinished silencer there exactly the same as what is in the short unit fitted to the TX.

It consists of a series of Nylon 66 cups each of which contain a baffle made of Fomex, a sound absorbing fibre, a spring to retain the fibre and an O ring to seal each unit.
Each unit is of a different length to cut down on harmonics so the length of one unit must not divide equally in to the others, the first chamber is the biggest, because it is the one to receive the most pressure, after that they reduce in sequence.

The problem with silencers is size, if you stuck a bucket on the end of your barrel it would work quite well, but it wouldn’t be practical, also the longer the silencer the better, it gives you time to strip the high pressure air out of the stream, so a short unit is the least practical of all.
You have to balance the volume you have available against the amount of baffles you wish to fit, too many and there is very little space left to store the high pressure air, and to few and you don’t remove enough high pressure air to make a difference, increasing the diameter of the tube to much, fails to make any impression either.

So really it is a catch 22 scenario, also everything depends on the fps the gun is shooting at, the higher the longer the silencer needs to be to work properly, another thing to think about is the sound absorbing material, this takes up volume but can remove high frequency sound, but after saying that HF sound does not travel far, so you could remove it and use the extra volume to strip off more HP air and reduce the down range noise, and one last thing a .22 is easer to silence than a .177, it has a lower fps for the same foot lbs.

Most manufactures of silencers make them to one size fits all, in other words .22 also they use length to make it work, and give a generous pellet clearance to avoid clipping, so if you want to make a smaller silencer you need to reduce the tolerances and make sure the silencer lines up perfectly with the rifles bore, the clearance I use is 5.5mm for .177 and 6.5mm for .22 and this applies to all baffles.

Foamex: is a type of plastic which is strong, light and absorbs sound.
The sound absorbing material is scotch pad.

I hope you can make sense of this

Al

BBGun Bob · Veteran Member

I understand your theory on different distances and the harmonics both being from different sources(Hp air and HF sound. I would have to say you have done alot of experments to come up with the right mixture in spacing and diameters as well as materials to use inside your mufflers.
With the information you have just given me I am sure I could build one.I made one years ago for a .22 rim fire rifle.It was rather long but very effective.But mine had the spacing betweem each chamber the same.That would probably account for the length that I needed to make it work.After I found out how much trouble this would cause me if caught by the law I scrapped it with a oxy- acetylene torch.Here in the States it is a felony to have one(even f it is not mounted to anything!!!) and an automatic 5-7 years in prison,,, no if, and ,or buts about it!
I have a friend who is a state senator I am going to ask him about this law and how it applys to air guns.If I can get something on paper I will give it a try.No paper signed by him ,No experments.
Kinda of a shitty law and I really don't even understand why,especially on air guns.
However you can apply for a license to have one for $2000 USD and then if approved pay a $200 USD tax even if you make it yourself.So it all boils down to the money.bullsh!t I say !!but they sure would be nice to have in an urban area where a neighbor may not like the noise.Those who are using them around here(there are a few) are calling them a LDC or lead dust collector. He! he! but if caught with a LDC your going to jail,the judge won't buy that story nor will the lawmen who catch someone.

Thank You For the Education
BBGun Bob

Alstone · Moderator & Site Supporter

Hi Bob
I used to originally build suppressers for .22 rim fire and .410 shotguns, and air guns are a different kettle of fish; they are simple when compared. For a basic unit use three baffles, no sound absorbing material and about 8” long, 1” to 1 ½ “ dia. This should work for 90% of all airguns under 12flb.

Have fun

Al

broommaster2000 · Moderator

cw · Banned

What is this?

CW

BBGun Bob · Veteran Member

It looks like a steel hot dog in a steel bun LOL

BB

Alstone · Moderator & Site Supporter

cw · Banned

It's very easy to get the required permit up here in
Washington. You just give them $250, wait a couple
of months while they check to see if you are a criminal,
crazy or otherwise socially unstable. Then you just go
down to the hardware store with a 10 spot and get
the materials to DIY.

This one tames 75 fpe to a hammer click.

It takes a minimum of 67 cubic inches of internal chamber
volume to tame the air blast generated by this muscle gun.

It is possible to shoot in apartment unnoticed with this
one. It is also my rockchuck device. I can usually get 5 or 6,
using it, before the whistle blows and they all dive.

It slips on and off in seconds.

I used thin wall 7000 series aluminum for the body tube
which resonated with a low ping sound that is counter
productive to effective rabbit/rockchuck pest control, hence
the foam and rubber wraps. The thin wrap is not as effective
as the faom one, but is more tear resistant out hunting.

I too, made one for a firearm once, my HK model 91 .308
(which is unbelievably loud), years ago when I first got it,
and I also destroyed mine when I learned of the consequences
of illegal possession. Get the permit, It's worth it.

CW

Alstone · Moderator & Site Supporter

CW how long is that moderator on your rifle, and does it slide back over the barrel much?

Al

cw · Banned

The device is 21.5 inches long.

The gun is 39 inches long, the barrel overlap is
6.5 inches and the overall length is 54 inches.

So it adds 19 inches to the overall length of the gun.

CW

BBGun Bob · Veteran Member

cw I'm not knocking you in anyway but that thing looks terrible on a beautiful rifle.(I'd rather have it make noise)
I think you should talk to Al about the proper way to build a beautiful LDC.He is a master on building them.
That thing you got I wouldn't but on a Daisy Red Rider or a POP gun.

Sorry buts that my personal Opinion

BBGun Bob

Alstone · Moderator & Site Supporter

I find it intresting to find out the volume and length of silencer for diffrent outputs, and to get 75pfe down to a hammer click with roughly 18" of effective silencer after you remove the barrel volume is pretty good, the only problem I can see is the total length of the gun, there again I suppose provided you are not running around in the woods then it's not a problem.

Nice job Thumb Up!

Al

cw · Banned

Yeah, I get that a lot. When I built it, I paid no
heed to aesthetiss. Performance was my only
objective. I had bought three moderators
(nice well finished, small and sleek) off of the net.
Highly rated ones touted to be near silent. They
worked magic. There was only one problem. Once
I surpassed 55 fpe, it was almost like I had taken
it off. The gun would still bark extremely loud.
It was useless for what I wanted it for (rockchuck
pest control). I would take my shot at about 80
yards, nail one and the rest would hear the report,
the whistle would sound and they would all dive back
into their burrows and I would have to wait 15-20 min
untill they would surface so I could get another shot.
With this setup, although not pretty, I can nail 5-6
before one of them sounds the whistle.

Pretty? NO! Effective and fun? 100 percent.

CW