Hello from the UK

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ant3000
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Hello from the UK

Post by ant3000 »

Hello everyone, I'm a nooby to silencers but not inventing.

So in the UK we can build any silencer/moderator for airguns. Ive got a hobby engineering shed so I've taken it upon myself to build a silencer that will bring the noise down to sub 90db. Ive got basically everything bar the fluid dynamics software.

So I've done some tests with my Kalibrgun Cricket Standard .22 running at 20 ft/lb:-
1)- I shot the gun into the garden hose, the pellet never made it out the end but the gun was basically silent, a 30ft tube must slow the gasses enough to silence this gun, but it can't be used to shoot.
2)- Made a basic 12" tube with a few end baffles which read 110db, then I drilled 10x 6mm holes into the tube and glued ten of those little one way air baffles that you get in fish tanks, this brought the level down by 10db, which is a moderate success but would stop the silencer from being screwed on.
3)- I built a 12" carbon fibre rod with 6mm internal and drilled loads of holes into it, this reduces the decibels by just 6.

My Studies - have got as far as making an air stripper and I'm about ready to try K Baffles, but my tests are making me wonder if its possible to build a strange silencer, because its only an air gun we are open to other options.

Ideas
1)- The Air Strippers I've seen tend to have 4 areas for the gas to go around the pellet, what if I fitted 4 extra external silencer tubes that received gas from each of these ports, and a one way valve might help.
2)- Ive also been thinking about a lever which blocks the silencer after the pellet, works with the air pressure. "I'm sure that won't work though", I've seen 4 designs on google that look like their 50 years old.


Question
Most companies try to make a miracle out of a 6" tube that screws on the end of the gun, no wonder they have trouble. But with free reign to make a silencer that really worked, has anyone ever managed to make anything other than a straight tube with trick baffles???

Could my 5 tube silencer actually be worth looking into or am I wasting another £70 worth of carbon fibre?

Or does anyone have any links to other ideas?

Thanks for any advice in advance
ant3000
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Re: Hello from the UK

Post by ant3000 »

Ive made massive progress with high pressures, the main tube shoots through a a 90 degree plumbing tube with a 7mm home in it. 90% of the air get directed into the larger tube which is bellow, basically I've gone from 107db to 87db and thats just a test with plumbing tube plus their are No baffles in the tubes. The top tube does rattle like a plastic tube would but a a few baffles and other tricks and we are in business.

Here is my surprise, I pulled the two tubes apart to add some acoustic foam beneath the 90 degree bend, when I put it back together it didn't match perfect and the tiny escaping gasses reduced the decibels.

Now it sounds like a deep thud.
a_canadian
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Re: Hello from the UK

Post by a_canadian »

Unfortunately your descriptions leave me puzzled. Perhaps others reading these posts understand... but then again, from the complete lack of response it seems likely that your designs aren't translating for most readers. Could you offer a picture or ten? Of the parts you're using, and the modifications to them, and the way they're assembled? Line drawings perhaps?

From my experience with suppressing airguns (PCP type, anywhere from 5fpe up to 34fpe, in .177" and .22") most of the noise can be removed by well designed, well crafted K baffles. Aluminum or Delrin (acetal) plastic seems to make little if any difference. The key is in making really efficient designs which manage the air flow effectively, getting as much as possible off the bore line. Going to as long as 8" can increase effectiveness, but longer than that I've heard little if any further improvement. A 1" diameter 8" long tube with 11" short K baffles works astonishingly well on my 8fpe Brocock carbine. Someone in the next room would not be aware of multiple shots into a soft cloth target. Shooting into putty, the pellet hitting the putty is much louder. I use a 7" long aluminum tube 1.375" diameter with 5 Delrin K baffles on a 30fpe rifle and it's almost as quiet at the 10fpe. I've tried a lot of experiments in monocore designs and various other baffle systems, but nothing seems as quiet as good K baffles.
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Re: Hello from the UK

Post by a_canadian »

Oops, forgot to mention something rather important in discussing suppression; dB numbers mean nothing in terms of absolute comparison unless you are using a VERY costly decibel meter with an equally impressive microphone attached, and the meter having been calibrated and tested according to standards which are proven to be acceptable across the industry. One sad example of misuse of decibel measurement is that of Jesse James and his 'sweet potato' suppressor. He's obviously fallen silent since his earlier boasts of having successfully reduced the report of a 5.56 rifle to about 89dB, which is patently impossible, no longer boasting of his industry-beating performance with his absurdly, even childishly simple suppressor design, though a couple of his friends seem to persist in recording and sharing videos... which show that the shots are just barely suppressed. While no one seems to know exactly which irrelevant meter he was using, it seems from that number most likely that it was a smartphone app, probably used on an iPhone. My own tests with various dB meter apps on a couple of good Android phones have come out similar or slightly higher for airguns, and only slightly higher readings for .22LR suppressed. I've purchased a cheap dB pressure meter and with that have recorded numbers a lot closer to those anticipated using the industry standard equipment, but still well shy of the proper measurements.

So I'm just suggesting that while your measurements with whatever device may be useful in-house for comparison of one suppressor to the next, don't make the mistake of thinking that these numbers are in any way meaningful for comparing to commercial or in fact any other suppressors as measured by other users, as the numbers have no relevance to each other. The nicest eBay-purchased SPL meter is going to show numbers at least 15dB lower at peak than a proper mil-spec meter and microphone. Cheaper meters are a useful aid for the builder in comparing his own builds but nothing more.
ant3000
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Re: Hello from the UK

Post by ant3000 »

[URL=http://s714.photobucket.com/user/a ... .jpg[/img][/url]

This is my Cricket and I've put a 30mm tube on top and a 40mm tube underneath, they slot onto the silencer and the pressure container. The 90 degree tube has a 7mm hole that lets the .22 pellet through but most of the air gets directed into the bottom tube.

Now I've found out it works I've bought carbon fibre tubes and I'm going to make the real thing. Obviously accuracy thought the silencer is an issue but I'm working on that. The results are amazing. Ive also found acoustic foam to be a big advantage too.

BTW, When making the test out of plumbing pipe I ripped it apart and put acoustic foam under the 90 degree tube, but the tine escaping gasses seemed to work very effectively. Im considering covering the silencer with the foam and drilling 2-3mm holes into the tubes.

If anyone can offer any suggestions id love to hear them???
ant3000
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Re: Hello from the UK

Post by ant3000 »

a_canadian wrote:Unfortunately your descriptions leave me puzzled. Perhaps others reading these posts understand... but then again, from the complete lack of response it seems likely that your designs aren't translating for most readers. Could you offer a picture or ten? Of the parts you're using, and the modifications to them, and the way they're assembled? Line drawings perhaps?

From my experience with suppressing airguns (PCP type, anywhere from 5fpe up to 34fpe, in .177" and .22") most of the noise can be removed by well designed, well crafted K baffles. Aluminum or Delrin (acetal) plastic seems to make little if any difference. The key is in making really efficient designs which manage the air flow effectively, getting as much as possible off the bore line. Going to as long as 8" can increase effectiveness, but longer than that I've heard little if any further improvement. A 1" diameter 8" long tube with 11" short K baffles works astonishingly well on my 8fpe Brocock carbine. Someone in the next room would not be aware of multiple shots into a soft cloth target. Shooting into putty, the pellet hitting the putty is much louder. I use a 7" long aluminum tube 1.375" diameter with 5 Delrin K baffles on a 30fpe rifle and it's almost as quiet at the 10fpe. I've tried a lot of experiments in monocore designs and various other baffle systems, but nothing seems as quiet as good K baffles.
Thank you for your input and I think I am going to try K-Baffles, especially because you said they can be made from derlin, which I fine easier on my hobby lathe. Can you offer me any other advice? BTW - MY DB meter registers 12fpb at 91 evertime but my new test silencer got 87 with 19fpb and thats without baffles, just acoustic foam in the end.

I wish I could buy K0Baffles at 28mm dia?
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Re: Hello from the UK

Post by a_canadian »

In respect to K baffles, I'd suggest reading and looking at the pictures in any number of discussions here. Silencertalk is full of threads discussing various aspects of K baffle design. Some are better than others, obviously, but if you read a few dozen discussions about this type of baffle as it relates to .22LR you'll get a fairly good idea of what applies to a higher powered PCP rifle suppressor. The red baffle about halfway down this page of a very ancient discussion represents a very solid K baffle design, the relation between the two asymmetric scoops being about ideal:
viewtopic.php?t=12863

But rather than picking through to find you what in my opinion might be the most efficient designs, have a look at a simple site-specific Google image search, where you can see a number of approaches and follow them up to read about how well they perform in many cases:
https://www.google.com/search?q=site:si ... yICh38vgDu

As for your metered blast levels... again, these mean nothing in terms of any sort of comparison to real world sound pressure levels. It's nice to have that relative number to compare with previous numbers of your own. But it is extremely unlikely that the actual sound level coming from your airgun is that quiet, measuring with the proper tools would probably show a figure closer to 100dB if not higher. The state of the art manufactured .22LR suppressors are able to reduce the report of a subsonic round fired from a bolt rifle to approximately 106dB. That's the best of the best, suppressors costing $800 or more with years of research having gone into their design. A 3dB drop is a dramatic improvement at that level. If you were achieving 87dB, that's orders of magnitude quieter than the quietest suppressed .22LR rifle, which considering your reported 19fpe power level (about 1/2 to 2/3 the muzzle energy of a subsonic .22LR round) just doesn't seem possible. Especially with a simple single-point air diversion system. The best suppressors use many points of pressure diversion, not one.

While wrapping with foam may be of some small use, I've not found that such measures have offered sufficient reduction in sound to merit the awkwardness of the much larger, more delicate suppressor which results. Effective suppression involves primary diversion, secondary working of the pressurized air/gas, and containment of that gas as long as possible. What you've been working on seems somewhat akin to an over-the-barrel approach except that instead of using a shaped blast baffle and vented spacers to push pressure back around the barrel, you're diverting it downward and again forward. A bulkier solution than an OTB, or integral approach, but I can see how it would be somewhat efficient. Introducing optimized shaping of the diversion port would seem quite important, and somewhat difficult as it involves a ready-made elbow joint rather than something more easily shaped like a blast baffle. If I were using a Kricket, I expect my approach would be to enclose the whole barrel plus about 4" to 6" ahead of the muzzle in an oversized tube, put short, well made K baffles in front of the muzzle, after an initial blast baffle without a cross-bore port which instead directed flow backwards through the ported barrel spacers. Keeping the blast baffle hole about 1/2" away from the muzzle crown and the hole size no larger than 6mm (the barrel maintaining alignment so that such close proximity to the 5.5mm pellet does not harm accuracy) would scrape a lot of waste air away from the bore and dump it backwards where energy would be lost while still contained by the over the barrel tube. The remaining K baffles (or long cone baffles would probably be fine) would provide further reduction of noise in the remaining jet of air, while keeping the rifle's overall length still relatively short. I've found that holes in K baffles out to about 8 inches length can remain at 6mm without issue, provided that the concentricity to the bore line is perfect. If there's any doubt about this perfection of alignment then going to 6.5mm may be necessary. 7mm and you start to get louder.
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Re: Hello from the UK

Post by ant3000 »

Hi a_canadian

Thanks for all your help and I agree with everything your saying. But I'm just a hobby guy with some OK equipment and lots of mad ideas, and I'm short of money to keep trying different ideas. Thats what I built my tests from plumbing pipe.

You might say my decibel meter is crab and no doubt it is but it is consistent [URL=http://s714.photobucket.com/user/a ... .jpg[/img][/url]

Im looking forward to making the K-Baffles next, especially now you tell me they are so effective. Id heard they were for powder rounds so they can be cleaned, thats why id not considered them.

Question - Ive thought about a 'Non return valve' in the bottom tube, with a few 1mm holes drilled in the tube. What do you think?


Many Thanks
ant...
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Re: Hello from the UK

Post by a_canadian »

I have an identical sound meter. And I agree, it is very consistent. Problem is the slow response time. This meter samples at far too slow a rate to be able to catch the very brief and intense sound from a firearm or airgun. What it's measuring is not accurate in an absolute sense, though in a relative sense as you say it is consistent. Only a meter which is capable of picking up much, much shorter intervals of sound will be able to capture the actual peak volume. But I like my little meter and use it to test builds, it's useful in comparing each to the next and finding whether there's been an improvement. A reading of 87dB with that meter, with the meter's mic pointed at the muzzle from one meter to the side, and of course measuring in the same location every time as room acoustics (or outdoor environments) can influence this meter quite a lot. I've tried testing the same airgun and suppressor in my workshop then again in the hallway, and find as much as a 4dB difference in readings, with the hallway tile floor apparently amplifying the noise for the meter. My ears confirm this, as shooting an airgun in the hallway is much louder than in my workshop. Shooting outside is quieter still. Standard testing with proper meters is supposed to be done on grass with, if memory serves, a grass height not greater than 4". The meter is supposed to be placed 1 metre to the right of the suppressor muzzle.

I've no experience with drilling tiny holes in the external tube of a suppressor. I did do some tuning work for a friend on his Talon SS, which was shooting at about 17fpe. The previous owner had followed advice given in some forum discussion, and had drilled 3 small holes through the main tube in the area under the forearm grip with the misguided notion that this would somehow quiet the already quiet airgun further. It did not. I tapped these holes and filled them with set screws, and the noise was reduced quite dramatically. Putting holes in the external tube seems to be a silly idea, unless as you say you cover them with foam... but then why drill them in the first place? I could see such holes having utility if you were using a dual-tube design, with some small holes allowing passage of pressure into an outer tube volume. This would perhaps be a useful approach in cases where an integral suppressor tube was not practical but you needed more volume in a shorter suppressor.
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Re: Hello from the UK

Post by doubloon »

ant3000 wrote:...
Thank you for your input and I think I am going to try K-Baffles, ...
You don't need K baffles for an airgun.

Google for the baffle stack from a Benjamin Marauder. I own a .177 that is mouse fart quiet with pellets exiting the muzzle in excess of 900 fps.

The baffles in my Marauder look like this, basically empty shotgun shells. Here's a write up http://www.pyramydair.com/blog/2009/4/t ... er-part-1/

Image
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Re: Hello from the UK

Post by ant3000 »

Hello doublebloom

Truth is I've been put off making K-Baffles because of the 60 Degree single flute countersink required to make the cone at the back. They go for mad money.

a-canadian - Yes cover the holes with foam and wrap with CF for stability. When I pulled my test silencer to bits and pushed it back together I found it was noticeably quieter when tied together with a rag. More testing needed though.

Thanks for the help guys :)
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Re: Hello from the UK

Post by a_canadian »

Dubloon likes saying that stuff. I have a feeling he's done an awful lot of firearm practice without adequate (or any) hearing protection, if he's hearing a 900fps airgun as 'mouse fart' quiet. There's no such thing except to those with significant hearing impairment. I've got a friend with a lot of years of military experience and range time as an instructor, millions of rounds fired, a considerable number (in the field) without hearing protection. He lip reads, and swears every suppressor on an airgun is inaudible. My hearing's fine. Never used firearms, though I did attend the odd punk gig decades ago. I tend to be overly sensitive to noise and can hear whispers from the next room (my kid hates that), and while I've heard some amazing suppressors used on PCPs, even from a 3fpe .177" PCP with an integral suppressor I hear a small burp. Very small, and not something anyone would take note of as being anything but some random little sound, but it's still making a noise. If you're pushing lead at any velocity at all, you're making noise, and the reason we're tending to call these devices 'suppressors' rather than 'silencers' more often is a matter of honesty; there is no such thing as a silencer.

You don't need a single-flute countersink for delrin. Just use any old countersink, then follow with a boring cutter on an angle. Takes a bit more fuss than merely drilling a hole with a countersink but it's dead easy on any lathe. Delrin doesn't put up a fight.
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Re: Hello from the UK

Post by doubloon »

Nobody said it doesn't make any noise at all.

Technically you're right, it's not Mouse Fart quiet, it makes less noise than Hollywood quiet.

Don't be such a hater. You don't even know the meaning of the terms you're parroting and you are just casting doubt and insults. For shame, for shame.

A Beeman R9 measures somewhere around 90 dB on a meter and the Marauder is even more quiet than that. When the Marauder is fired the loudest noise is the sound of the striker hitting the plunger. I've seen Marauder numbers posted on the interwebs that put it in the mid 70 dB range for .22 and quieter for .177

Allow me to educate you on the terminology.

Suppression dB ratings

153-190 -- if I were you I'd sell that KelTec RFB
147-152 -- unless that's a 50BMG you got ripped off
141-146 -- are you sure those rounds are subsonic?
135-140 -- you didn't spend enough
129-134 -- loud
123-128 -- quiet
117-122 -- stupid quiet
111-116 -- giggly quiet
105-110 -- mouse fart quiet
100-104 -- is that an air gun or did you forget to load it?
000-099 -- Hollywood
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Re: Hello from the UK

Post by a_canadian »

Sorry, wasn't trying to be a hater. More teasing than anything. Guess I should try to make myself use the idiotic smileys... It's just that you've said this once or twice before in the forum, that airguns don't 'need' fancy baffles like K's and such. What you're showing is essentially washers and spacers, though they're integrated as washer-spacer pieces (though why anyone would want to go to all that trouble I have no idea, when it's EXACTLY the same acoustical effect as washers and spacers). I've made a few washer and spacer cans. I've even incorporated a bit of scrubbing pad or steel wool in early experiments, as that's stuff the Brits seem to think works well. But I've never heard one of those systems anywhere close to the suppression of a good set of K baffles. Dubloon; if you have an air rifle with a threaded barrel which can accept one of your firearm suppressors, why not give it a try? Especially one with good K baffles. You might be surprised to find that it actually gets considerably quieter than with mere washers and spacers.

I made a set of delrin K baffles for that friend's Talon SS, replacing the factory white delrin things which were virtually identical to the ones you're showing from your Marauder but plastic. The suppression with those simple factory baffles was adequate. But my friend has a suburban squirrel problem and neighbours, and doesn't wish to get himself noticed while dealing with the squirrel problem. He wanted it much quieter. So I made a stack of plastic K baffles. It's substantially quieter. So much so that I would feel completely comfortable shooting that rifle in a densely populated neighbourhood with people out on their balconies, knowing they'd only notice me if they saw me shooting. It's that quiet. No way would I risk doing so with the factory washer/spacer nonsense. Same air volume, just taking advantage of the blast re-direction only a K baffle can do well. There's a reason K baffles are so popular with .22LR users but not so much with the higher energy firearm rounds. K baffles really shine at lower energies, where gas flow can be more successfully directed by such strategies.

I meant no offence, really, and am sorry that I seem to have offended you. Netiquette is an ongoing project... maybe I'll never be good at it.
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Re: Hello from the UK

Post by doubloon »

a_canadian wrote:... though they're integrated as washer-spacer pieces ...
I meant no offence, really, and am sorry that I seem to have offended you. Netiquette is an ongoing project... maybe I'll never be good at it.
That's essentially what they are from my perspective as well, washers and spacers or freeze plugs. Some very well performing 22lr suppressors have been made from freeze plugs by the way.

I'm not saying the design and materials found in the Marauder couldn't stand some improvement. There's even some guy out there who "fixed" his with masking tape to get rid of the rattle. Ha!

At any rate, just letting the fella across the pond know he doesn't have to over think it.

Unlike an actual firearm all the gas that's ever going to pass out the muzzle is released all at once in an air gun ... big air bang. There's no fire, no unburnt powder still expanding in the suppressor and no heat worth talking about.

It's really a much simpler problem than a real firearm suppressor. It should be fairly straightforward given the size of the reservoir and the atmospheres of pressure for any given PCP rifle with a particular barrel size to approximate how much gas is going to expand into the suppressor before the pellet exits and at what pressure it's going to exit once the bore is free of the pellet. http://www.kiledjian.elac.org/phys%2000 ... %20Gun.pdf

As for the offense. Not so much "offended" as addressing your fallacious arguments of dismissal, ad hominem, straw man and a little bit of argument from authority. :D I thought my "chastisement" was equally as tongue in cheek as your "attack". I mean "For shame, for shame" who really talks like that? Maybe a nun on TV from the 1950's.

ETA: ... you don't know ... I might be a TV nun
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Re: Hello from the UK

Post by a_canadian »

All good then. Well for me it's a matter of nuance. With firearms, especially for those who choose supersonic ammunition, the focus is largely on the user experience. A suppressor's purpose there is for the most part one of health and comfort. With airguns there's not so much of that, though the more potent big bore PCP stuff such as some use for hunting big game can of course deafen the user just as easily as any firearm. But for most, using a suppressor on an airgun is more a matter of courtesy/privacy. I got into making them after consulting with a fellow working with the RCMP in firearms licensing and violations. He researched the law carefully, and came back to me saying that so long as I made them for airguns and used them in my home there really wasn't a problem. He went on to say that he'd not want to be the 'test case' for such an action, as judges are something of a random element... but so long as I didn't do anything stupid like use one in the commission of a crime, brandishing or such, that I'd be fine.

So I've pursued that, primarily in aid of being able to practice my shooting at home without disturbing the downstairs neighbours. Or making my wife flinch too much. Shooting with as little sound as possible is the goal here, not hearing protection, as none of my airguns is capable of damaging my hearing, though a couple are annoyingly loud unsuppressed. Going from washers and packing to monocores was a big step in being quieter. Going from my best monocore to my worst early K baffle was another big step down in noise. Now that my K baffles are rather refined, noise is as quiet as one could hope for in a home target shooting situation. No one flinches, no one gets annoyed, and at times my wife and kid are even surprised to find that I've been shooting, if the radio is on with news chattering away for example. So while I could get away with washers, K baffles are vastly superior with my airguns.

Tuning also plays an important role of course. An airgun which is dumping excessive volumes of pressure long after the pellet's been pushed hard enough are very loud and require too-frequent filling by pump or by tank. Learning to fine tune the valve and hammer operation is critical in achieving an efficient 'load' for a given pellet, just as one must learn quite a bit to properly load one's own firearm ammunition. Reducing wasted air to a minimum leaves the job of suppression quite a bit easier, while also providing more consistent velocities throughout the fill pressure range for more accurate shooting. Most commercial airguns are inherently wasteful as supplied by the manufacturers and need fairly extensive surgery and experimentation to develop a satisfyingly balanced performance. Not much point reinventing the suppressor if one's airgun is dumping twice as much as necessary for a given power level.

And yeah, sorry, I actually thought you meant it when you wrote 'for shame, for shame.' Bunch of TV nuns around here...
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Re: Hello from the UK

Post by doubloon »

All good stuff.

Yep I wouldn't want to try to suppress one of the big bore PCPs, 22s and 177s are much easier to tame.

That's the whole reason I never owned a PCP until the Marauder was released, always been a springer fan. My R9 competes very will with the Marauder on velocity and power but the Marauder is actually much quieter.
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Re: Hello from the UK

Post by ant3000 »

So I'm about ready to make my K-Baffles, especially because they can be made from derlin and I've found a 60 degree countersink in the UK.

Ive read this article on making whisper quiet K-Baffles, under the silencersmithing section viewtopic.php?f=10&t=17116.


Question
Please can you offer me any advice on how to make the perfect PCP K-Baffle or anything else which would help my process?? I ask this because 'a_canadian' mentioned something like a well made K-Baffle does an amazing job. "Perhaps I won't need that cumbersome bellow silencer barrel"

Image

Thanks in advance
ant...
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Re: Hello from the UK

Post by a_canadian »

I've modelled mine somewhat after these:
Image
Shorter and more of them seems to deliver better suppression. An overall length of each baffle (in a 0.875" inside diameter tube) of between 0.55" and 0.65" seems to be about right, with a more 'K' shape than the usual sloped 'L' shape which is commonly called a K works well, allowing the face profile to be cut deeper with less material remaining in the baffle than when using flat front pieces like in your pictured examples. The clip on the edge of the cone does not improve performance in my experience. Actually makes things slightly louder. Stick to the sort of cross-bore porting you see in your examples but keep the K shorter, in proportion to the tube you're using, and you should be fine. The main thing is to think about that cross-bore jet, how to very aggressively push part of the forward stream across the bore and out into the outer area without making that exit hole so large that pressure can get back into the bore easily.
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Re: Hello from the UK

Post by ant3000 »

First - Would you consider making me a dozen of those K-Baffles 28mm diameter?

Second - Ive made my own 70 degree countersink from mild steel, obviously it wouldn't work on alloy but it does a fine job on Acetal plastic rod.


This is a bit confusing, is this what is normally referred to as the mouse hole?
The main thing is to think about that cross-bore jet, how to very aggressively push part of the forward stream across the bore and out into the outer area without making that exit hole so large that pressure can get back into the bore easily.
If it is the mouse hole then with a 28mm dia K-Baffle, what size drill should I use?

Thanks for your help again :)
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Re: Hello from the UK

Post by a_canadian »

The term 'mouse hole' gets thrown around for a couple of different things, but as I understand it the main usage is those cuts into the wide end of the cone, the cut I'm suggesting isn't a good idea. It lets pressure back into the bore line too easily. The two asymmetric cuts you need are as shown in the drawings above and the photo I referred to. One from inside the cone, cutting with a ball end mill (not a drill) into the waist until a pocket has been formed and a small escape hole into the outer volume, outside the cone. The second is also cut with a ball end mill, this one from the face side with the bit approximately centred (this location can be a matter for experimentation, and is part of where the 'art' of K baffle making comes into play) on the outer edge of the bore hole. It is 180 degrees from the inside cone cut. The result is that the initial impact of pressure on the face is partially directed almost straight across the bore from that face cut, then out through the waist exit hole. For .22" you'd use a 0.25" ball end mill, or the same size bit as used to drill the bore if you're going a bit bigger than 0.25". You're trying to make the pressure zig-zag as much as possible to obfuscate flow.

The diameter of the K baffle has nothing to do with the size of the bore hole and the size of your milled cross-flow ports. Those tools are chosen based on calibre.

As for making and mailing suppressor baffles... no, I do not wish to spend time in prison, but thanks for asking.
ant3000
Member
Posts: 36
Joined: Tue Jun 02, 2015 3:03 pm

Re: Hello from the UK

Post by ant3000 »

Ive just made a dozen K- Baffles out of Acetal rod, I did;t have the fancy 60 degree countersink so I used a 24mm hss drill, but whats amazing is that I haven't even drilled the mouse soles yet. Im looking forward to testing acoustic foam with the baffles too.

Its wipes the floor with my double chamber model.


Question:- I've got a dozen short K-Baffles, they are going in a 30mm CD tube. Can you offer any help with spacing or air stripping etc???


Thanks
ant...
a_canadian
Silent But Deadly
Posts: 1204
Joined: Fri Oct 11, 2013 3:09 pm

Re: Hello from the UK

Post by a_canadian »

Not quite following. So you're happy with the performance, even when using a drill to hollow the 'cone' side? Doesn't seem likely it'd be much of a cone, but if it works, great. Spacing? Air stripping? K baffles do both. What more is wanted?
ant3000
Member
Posts: 36
Joined: Tue Jun 02, 2015 3:03 pm

Re: Hello from the UK

Post by ant3000 »

No Mate, that K-Ballef design pissed all over my designs and I could'nt be happier.

Tonight I drilled that little hole so the air could get through to the outer cone and I believe its even better.

What I'm really gratiful for is the fact I don't need to carry two silencers, one for 12 and one for 19ftp.

Many Thanks
ant...

PS - Is their any recommended distance between the blast at the end of the barrel and the baffles?
Last edited by ant3000 on Sun Jun 21, 2015 5:37 pm, edited 1 time in total.
a_canadian
Silent But Deadly
Posts: 1204
Joined: Fri Oct 11, 2013 3:09 pm

Re: Hello from the UK

Post by a_canadian »

I've tried the spacing anywhere from 4mm muzzle-to-first-K and up to 4cm. Haven't been able to say for certain there's a significant difference. I have found a slight improvement when I use spacing something like this, with = being a spacer about 1cm, K being a K baffle, and | being the front end cap:
=K==KKKKK|
It seems that adding about 2cm or even a bit more after the initial K baffle is helpful. Less work too. Wouldn't know how this would play out with rimfire, but with a PCP anywhere from 10fpe to 25fpe it seems to offer a slight reduction of noise. More volume to expand into I suppose.
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