Post By jacksonpollack
Supressor and Baffles Question
Before I start. In New Zealand, where I live, Supressors are legal so I am not trying to make something that could land me in trouble here.... LoL
I bought a suppressor for my .22 not too long ago. It is not working bad but thought I could build a larger one that might work better by allowing for more space in the chambers and more chambers.
OK, Ill try to describe what I did here:
All the chambers are 22mm in diameter. 1x40mm long, 1x30mm, 1x20mm, 1x10mm, 4x5mm. Each baffle only has the hole that the bullet travels through a 7mm hole as was measured on the other supressor. measuring the .22 bullet it measures 5.6mm which gives me about 0.7mm gap between the bullet and the wall of the baffles...
I finished the suppressor last night and tested it today but must say I am a bit dissapointed. The little one only has two chambers about 15mm in diameter and about 60mm long and it is still a lot quieter than the bigger one I built... I am not sure why this would be... One thought is that I might have to drill small little holes in the baffles to allow the gasses to expand to the other chambers too, but this should be possible through the hole the bullet travels so I am not sure.. I tried to attach the plans of what I built to give you an idea of what I have done but that did not work, so if you want more detail and thing you might be able to help me them please let me know if I need to send you the plans, they are in PDF format...
If someone can give me advice on what I can do to make the suppressor I built to do its job better it would be much appreciated.
Although I'm far from expert on the matter, it sounds like you've built a can with a stack of flat baffles, which basically give you multiple expansion chambers but little turbulence, which is really what causes the noise reduction.
Most .22 suppressors use K baffles. You can learn much more by registering at http://www.silencertalk.com and looking in their 'smithing forum.
I'm no expert either, but from building internal combustion mufflers of that ilk, I would say that the smallest chamber should be the first one that the blast encounters. you may have it this way, but from the description it sounds (NPI) the other way around.
This may be helpful. This is how I make my K baffles.
Some more information; http://bbs.homeshopmachinist.net/showthread.php?t=35021
One thing Hiram Maxim discovered when he was designing suppressors is that there needs to be an expansion chamber at the inlet end of. For his Model 1922 22 rimfire suppressor the baffles didn't start until about 2" down the tube. Then the remaining 4 or so inches was baffled with stacked, stamped sheet metal baffles that looked like distorted miniature bottle caps. The tube dia was 1" or maybe a little less. It's been awhile since I have seen the internals, so my dimensions may be a bit off. They are close. Anyway the suppressor worked very well, I thought. With subsonic ammo in a rifle out in the open, the firing pin click was nearly as loud as the muzzle blast.
I have a question is this k cone also usable on a larger cal such as the 30 cal or the 338.federal? Im thinking on he 338 . on a styker with a 14 inch tube or maybe a 16 i think this would be a intresting build
Thank you very much for all the replies...
First of all. Yes the baffles in the one I made are flat. I suspected from the start that this might be the reason why it is not working very good but what confused me was that the much smaller silencer I made only had one flat baffle in the middle of it held in place by two compression springs on either side of it...
My brother suggested that it might be because of the compressio nsprings that it might be working better... His argument is that while the gasses expand into the first chamber it forces the baffle to move forward slightly and then as the bullet goes through to the second chamber along with some of the gasses the baffle comes back... But I am not too sure if this will have much of an effect if it is the shape of the baffle that needs to cause turbulence in the moving gasses that will cause the silencing effect...
I have one end of my silencer threaded so I can allways do away with the flat baffles and make up some K-baffles. I did notice however that there ares lightly different ways of creating the mouse hole in the K-baffle. Is there any reason for one method to the other or will it work as long as the gasses has some place to escape into the rest of the chamber?
Suppression works by slowing and controlling the expanding gases and to a lesser effect, absorbing heat (i.e. energy). The mouse holes create a “cross jet” of turbulence that disrupts those expanding gases. The mouse holes are 180º from the bottom to the top.
The bottom of the K baffle collects the pressure, and the mouse hole directs the jet of gas across to the top mouse hole creating the cross jet effect, thereby delaying the gas out the front, and absorbing energy. Also used in centerfire suppressors.
In a previous post there is a photo of a John’s Guns integral. Note the copper wool wrapped around the barrel. That copper wool was wrapped around the ports to absorb the heat (energy). This increased the effectiveness of the poor designed baffle system. These heat sinks, are not used for muzzle cans, and have mostly been phased out of modern integrals.
Cone shaped baffles are the best in my opinion. I have used K shaped and 60 degree cones, but will try step cones next. Any baffle that makes the gas flow reverse onto itself is going to do a much better job than a flat baffle.
I would make the baffle bore at least 1 millimeter larger than bullet diameter to prevent baffle strikes that ruin accuracy. If the silencer does not align perfectly with the bore, make the bore larger as they get farther from the muzzle.
I think smaller expansion chambers are better. Use a tough metal like stainless steel for the blast baffle to resist erosion. The more back pressure and turbulance you create, the better the suprpession.
I use spacers and end cap compression to keep the baffles in place. Springs just add too much weight.
Your sprung moderator sounds like the "Manders" .22 moderator that came from Kiwi-land in the 1980s. I tried one (once!), but found that the front end baffle never returned to the same place and both noise and accuracy were poor, so it got relegated to use as a thread protector, and the Parker Hale went back onto the gun again
Have you seen the Frankford arsenal report on silencers?
Although they were testing old designs, frequently with rubber "wipes" (wear out fast and destroy accuracy - until they wear out), they did a pretty good job of using an oscilloscope to identify where the different sound peaks were coming from.
Interestingly, a Maxim moderator was one of the most effective ones they tested.
Many people will poke fun at the old Maxim suppressors as being old and out of date. But look at the results of testing. Many of Maxims test very well compared to modern ones and they are very simple.
Remember Maxim was making things in a different time, cheap and in bulk was the important thing, remember it was an unrestricted product for the general shooting public. Getting the firearm reduced to an acceptable level of noise was what was important.
People will debate about who is making the quietest design, but the difference is often so subtle that only a meter can distinguish and often the firearm and ammo will have a large effect on which is going to work the best.
Long story, short. Look at the old Maxim designs, they were very simple and worked well. There were a lot of marginal designs that were made by fancy engineers in during the Vietnam era that were worse then what Maxim had made a long time before.
I finished my AR-15 step cone silencer and shot it against the K baffle silencer I made last year. The step cone can was shot on a 16" carbine and the K baffle can was mounted on a 20" Hbar. The shooters said the step cone can was a bit louder and higher in pitch, probably due to the shorter barrel.
YouTube - ar-15's with homemade silencers The order of the shooting is unsuppressed, K baffle then step cone.
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