Testing the effectiveness of a suppressor

[sspbass]

Is there any generally accepted method for accomplishing this?

I've got access to a decibel meter used by the local pd to test for things like noise complaints etc.

My thought is that one could build a big box with some sort of sound dampening material lining it.
You could have access holes to insert the decibel meter at different locations i.e. in front of the barrel, behind the barrel etc...

I would like to see real numbers on what affect any of my "improvements" are making.

[Dr.K]

First off, in no way am I trying to insult you by any of what im about to say.

I can always tell when someone is new to silencers, and I have my own little name for them "decibel chasers"

I was this exact same thing when I got into this. I studied charts, comparisons, videos, and used real cans when I had the chance.

The longer I've been around, the less it matters, I can take the exact same combination of equipment, and shoot it at different times and it sounds different each time. Even night vs diay changes the sound.

The proper equipment can be set up and calibrated correctly and give different results for different people. I thought a few decibels mattered a lot, as it turns out, not so much. If you can tell a difference its more than 5 decibels anyhow, and that is the threshold of the human ear. It's so so subjective in the real world.

I think there are two places for decibel chasers. The r&d department of silencer companies, and new guys.

Again, I offer no disrespect to you. It is an idea I've pondered myself. But being around a whole bunch of silencers for many years, I'm happy to find myself not caring about a few decibels I can't discern.

I do know that clipping the cones made a discernible decrease in the heard sound of my personal projects.....but just barely enough to notice!

[sspbass]

The engineer in me wants to have hard data to prove or disprove any attempted improvements.

Do you pretty much just pick the best baffle for your application and then go with it?
I keep reading all of the little nuances people post about how they are going to do their baffles and I wonder how much difference it can make.
The way you put it most of that is in vain. Correct?

[CMV]

Trust your ears. What if you had a lower decibel reading but at a different pitch that to you sounded worse? Would you have made an improvement?

Do you or any shooting buddies have any suppressors now? Just compare your project to those. You'll notice if you're making improvements. On my two 22 projects, they sound different. I can't say if one is louder than the other, but the tone is a lot different.

Even the ammo you use will sound different. I notice a difference among brands even if they're all subsonic. Not much, but CCI std vel sounds different than SK Std+ for example. It wouldn't surprise me if you could get better results experimenting with different burn rate powders than tinkering with your finished can. Maybe not, but you'd think with the range of different burn rates for powders for a given caliber there's probably combinations that work better/worse in a particular weapon/suppressor combo.

Use a good design, machine it with good tolerances, and you'll be happy with the results.

[Capt. Link.]

During WWII and Vietnam there were suppressed weapons that are legendary for being silent.Today its easy to build a suppressor that is at least 10-15db quieter than the best ever made in that time period.I think that if you follow the recommendations of this board and do your part in construction you will have a suppressor you can be proud of.

To answer your question I will tell you it will cost about 20,000$ to build a lab based meter to measure a suppressed gunshot.The last portable meters were made about 20 years ago and if you can find one will cost 5,000 or more.You must have circuitry that can respond in under 20us and the best made today is about 35us your PD unit I doubt is under 150us.Its impossible to correlate the slow rise times to a reading that is higher or lower than the one before due to the brevity of the peek reading that will be missed because of slow response.If you wish to build your own pm me and I will send you a link that will get you started on what equipment is needed for a proper meter.

[Historian]

Include how one of our distinguished members tested his can once:
he fired it outside his open kitchen window and no one in the house
even noticed.

My evil "George Carlin alter ego" still laughs uproariously at the
cartoon of a man, can, cat, silencer on his pistol, once sent me
from an equally ribald member here with
the caption:

"Who needs all that fancy sound testing equipment? Just shoot one meter from your
sleeping cat. If the critter leaps up, limbs splayed, howling like the
devils of hell are chasing it, after you pick yourself up from screaming
in laughter, redesign your damned can or add more K-baffles."

[MCKNBRD]

"Who needs all that fancy sound testing equipment? Just shoot one meter from your
sleeping cat. If the critter leaps up, limbs splayed, howling like the
devils of hell are chasing it, after you pick yourself up from screaming
in laughter, redesign your damned can or add more K-baffles."

QFT!

Or, as one astute member here demonstrated his .22 can to me: we walked out back of his house (in a fairly crowded subdivision) at night, fired 10 rounds through his 22/45 into a berm 10 yds from his back door & 25-30 yds from his neighbor's cat sleeping on the recycling bin on his back deck. No one was the wiser, but the cat was fairly annoyed that someone dared venture into his 'domain' without permission, as felines usually are.

Byrdman

[a_canadian]

Lacking sophisticated testing apparatus to perform the standard 'milspec' test (one metre to the left side, one metre above grass of a certain height of growth, etc) I just go with subjective listening and rating. Comparing to a known very quiet standard is helpful. A suppressed .22" PCP pistol through a 7" stack of step-cut plastic K baffles is one such point of reference, with the same pistol unsuppressed providing a rather loud standard. Shooting such standards alternating with a .22" LR pistol with subsonics offers a useful gauge of how baffles are working. If the powderburner is somewhere around halfway between the two other sounds that's not too bad. To get significantly more sophisticated in measuring would require a rather absurd expenditure for private use. Comparing indoors and outdoors seems perfectly adequate for am individual developing a suppressor for non-critical applications like quiet, comfortable plinking. Asking a family member or friend to listen and attempt to describe the sound in relation to other non-firearm noises can be helpful as well.

[twodollarbill]

If you've ever watched Mythbusters when they do a sound test.
They call this "one guy" and his equipment looks really expensive.

[JFettig]

My understanding from a quick search around here is that if you want to meter them, you must use a really nice sound meter like a B&K 2209
viewtopic.php?f=2&t=110294
http://www.youtube.com/watch?v=FPsb2XEegRU

I'm personally using CFD to analyze my suppressor design, I've built one prototype so far(with a local SOT) and will be building some more for comparison to verify my results. If using CFD, its very important to understand the mechanisms going on, how to set up the inputs and how to interpret the results. Just throwing numbers in and looking at the pretty pictures won't do you much good. It is quite interesting to compare some design principles I see in commercial designs and see how they react to design changes in the simulations.

[Historian]

My understanding from a quick search around here is that if you want to meter them, you must use a really nice sound meter like a B&K 2209
viewtopic.php?f=2&t=110294
http://www.youtube.com/watch?v=FPsb2XEegRU

I'm personally using CFD to analyze my suppressor design, I've built one prototype so far(with a local SOT) and will be building some more for comparison to verify my results. If using CFD, its very important to understand the mechanisms going on, how to set up the inputs and how to interpret the results. Just throwing numbers in and looking at the pretty pictures won't do you much good. It is quite interesting to compare some design principles I see in commercial designs and see how they react to design changes in the simulations.

Sincere kudos on your talent. I especially appreciate what you are doing since
in the 1960's I foolishly believed that Heath Kits were easy for anyone to build
given the detailed pictured steps. Ho, Ho, Captain Midnight. Built a Variac* ... solder
all over the place, rescued by my EE buddy who repaired in 5 minutes my all day effort.

"Stick to theoretical, please!" he gasped.

Will there ever be a redux of Heath Kits:
"Build Your Own MIL-SPEC Suppressor Testing Meter; $88.00" ?


* << http://www.iseincstore.com/3pp1010bvari ... Ogod3h4AjA >>

[57fairlane]

My understanding from a quick search around here is that if you want to meter them, you must use a really nice sound meter like a B&K 2209
viewtopic.php?f=2&t=110294
http://www.youtube.com/watch?v=FPsb2XEegRU

I'm personally using CFD to analyze my suppressor design, I've built one prototype so far(with a local SOT) and will be building some more for comparison to verify my results. If using CFD, its very important to understand the mechanisms going on, how to set up the inputs and how to interpret the results. Just throwing numbers in and looking at the pretty pictures won't do you much good. It is quite interesting to compare some design principles I see in commercial designs and see how they react to design changes in the simulations.

The national instruments sound/vibration kit is the most "affordable" option.

B&K is way overpriced IMO and having run both B&K Pulse and NI setup, you realize testing for db levels of gunshots is like .001% of what either of those programs can do.

Unfortunately you have to pay for a ton of capability you won't ever use but you have to have that stuff to record it accurately.

[Baffled]

How about lame dB meters as comparative tools? In other words, you've got 3 suppressors you want to test.

Set up your tripod, your bench rest. Get measurements from each can using the cheap meter. Note the readings. Lowest wins. The point being, you cannot then say "My can metered XYZ decibels", because XYZ is not an accurate reading, but using it to compare silencers same day, same orientation, might work.

With that said, I agree 1,000% that the good old ear works fine. Some cans sound better purely due to the tone, even though the actual dB reading might be higher than another can.

[silencer_kid]

for scientific measurements one really needs a spectrum analyzer that divides freq spectrum and records db per division. measuring depends on the purpose of the item. is it a military grade item where the intent is to be silent to enemy receivers of any kind, or is the purpose to be able to shoot at the range w/o heavy ear muffs. the next question to ask is, does the sound need to be silent at muzzle blast, or does it need to be silent 100yds away?

sometimes a not-so-accurate meter is ok. as example, for relative testing (one can vs another), even a meter that is off by 5db from calibration is fine. however, if you want absolute measurement (one can only) than some form of calibrated measuring device is probably in order.

also, for real #'s testing really needs to be done in a lab environment, not in the open woods.

all of the commercial cans i have seen available to the public seem to be recreational devices. thus i think there is opportunity for you the designer/machinist to make something better.

[Capt. Link.]

for scientific measurements one really needs a spectrum analyzer that divides freq spectrum and records db per division. measuring depends on the purpose of the item. is it a military grade item where the intent is to be silent to enemy receivers of any kind, or is the purpose to be able to shoot at the range w/o heavy ear muffs. the next question to ask is, does the sound need to be silent at muzzle blast, or does it need to be silent 100yds away?

sometimes a not-so-accurate meter is ok. as example, for relative testing (one can vs another), even a meter that is off by 5db from calibration is fine. however, if you want absolute measurement (one can only) than some form of calibrated measuring device is probably in order.

also, for real #'s testing really needs to be done in a lab environment, not in the open woods.

all of the commercial cans i have seen available to the public seem to be recreational devices. thus i think there is opportunity for you the designer/machinist to make something better.

A military snipers requirement is very different than the police officer or the recreational shooter or for that matter the 007 types.
You are correct about the spectrum analyzer I have two in the house but don't have the amplifiers that will respond at under 20us.5 db off from calibration is a huge amount and would not be acceptable for development reasons.Its not the calibration that hurts it the speed at which the device will respond.A lab or the woods will not matter its like saying a gunshot is louder inside than out doors.I'm speaking of real peek reading not what is perceived.I'm in favor of using the cat next door but a few friends comparing one known can against the other will work in the place of proper equipment.
Welcome to the forum!

[gunny50]

all of the commercial cans i have seen available to the public seem to be recreational devices. thus i think there is opportunity for you the designer/machinist to make something better.

Kid that is a bold statement as many of those commercial cans are in use with police and or military, in and outside the US.
Sure some are better than others, but you can also try to supprise us with some new ideas?

Gunny

[silencer_kid]

all of the commercial cans i have seen available to the public seem to be recreational devices. thus i think there is opportunity for you the designer/machinist to make something better.

Kid that is a bold statement as many of those commercial cans are in use with police and or military, in and outside the US.
Sure some are better than others, but you can also try to supprise us with some new ideas?

Gunny

a bold statement? how so. many LE items (ammo, firearms, vests, etc etc) are not available to the public (although i buy some Federal LE ammo for my .45). i can assure you, the best item a Seal has you wont see in the public or used by local or state LEO, ever.

my point was, the items you reference are "cheap" to make, general purpose items that work very well, and meet the requirements of the buyer. there is plenty of room for physics to prevail for a design that is in fact better than a bunch of K baffles. the only surprise you might see is when i post db numbers.

[a_canadian]

Mind if one asks what sort of dB measuring apparatus you are going to use? And will there be a video of this testing to verify concurrency of the readings with the shots? Not that don't trust you... I don't know you however, and given the animus already arising around your somewhat arrogant remarks you'll perhaps understand the request.

[silencer_kid]

Mind if one asks what sort of dB measuring apparatus you are going to use? And will there be a video of this testing to verify concurrency of the readings with the shots? Not that don't trust you... I don't know you however, and given the animus already arising around your somewhat arrogant remarks you'll perhaps understand the request.

likely a spectrum analyzer connected to my laptop. that's the "sort of" apparatus it will be. actual make/model still tbd.

[a_canadian]

I don't understand your need for the snarky tone 'kid.' Sort of. As in what sort of, what kind of. Is that offensive to you somehow? I only asked, as it seems the consensus generally in the industry is that only a few types of hardware are actually capable of capturing the very briefly intense sound peak of a gunshot. Most microphones are simply incapable of responding quickly enough to get consistent and accurate readings. If you're looking for a fight (and from MANY of your posts here it seems that may well be your most significant interest in joining this forum) then you're going about it the right way. However my interest is purely in gathering information. If you wish to share information about your design or at least the results gleaned from it once built, great. If you don't mean to share... well, why are you here?

[silencer_kid]

I don't understand your need for the snarky tone 'kid.' Sort of. As in what sort of, what kind of. Is that offensive to you somehow? I only asked, as it seems the consensus generally in the industry is that only a few types of hardware are actually capable of capturing the very briefly intense sound peak of a gunshot. Most microphones are simply incapable of responding quickly enough to get consistent and accurate readings. If you're looking for a fight (and from MANY of your posts here it seems that may well be your most significant interest in joining this forum) then you're going about it the right way. However my interest is purely in gathering information. If you wish to share information about your design or at least the results gleaned from it once built, great. If you don't mean to share... well, why are you here?

OMG, i said TBD. i dont know yet. i haven't looked at mic's in quite some time.

[Fulmen]

i think there is opportunity for you the designer/machinist to make something better.

In your dreams perhaps. The companies that makes cans has research budgets, equipment and knowledge that few individuals can match, they could do more in a week than most of us can do in a year.

[Capt. Link.]

the best item a Seal has you wont see in the public or used by local or state LEO, ever.

I know of no item that is firearms based that is not known or that must be kept secret.The few items that are not in the public eye would be of little interest to sport shooters or LE.You even suggesting items on a public forum could exist tells me you have no Intel.

likely a spectrum analyzer connected to my laptop. that's the "sort of" apparatus it will be. actual make/model still tbd.

Post your equipment I used to work at White Oak! and have worked with David Taylor as well or don't you know Dave.

[Baffled]

There are no "secret guns" or "secret silencers" in use by any branch of the U.S. military.

[silencer_kid]

There are no "secret guns" or "secret silencers" in use by any branch of the U.S. military.

unless you work inside with a Seal team, and are breaking secrecy oath, i am rather certain you are 100% wrong. but hey, believe what you want.