A Gun You (ALMOST) Can't Hear at 85 Yards

[OldSpook]

Just for giggles, today after I got back from a Squirrel hunt I decided to see what my Talon P sounded like at 100 yards. The gun is running a moderator design I call the "Krait". The moderator is 40mm x 127mm and is for all practical purposes an enlarged "Ember" which we have had so much success with.

I expected I'd be able to show that the gun was almost undetectable at 100 yards. I got out the LASER and went next door to shoot thinking the yard there was 100 yards long but it wasn't it was 85 yards so I ran with that. A little math and I'd be able to talk about the noise level of the gun at 100 yards, or so I thought.

The gun is shooting JSB 15.89s at 800 fps. I tweaked the tune a bit yesterday and reduced the muzzle energy from 26 fpe to about 22 fpe. I noticed it quieted the gun some. Today when I was hunting I took a couple of practice shots and thought to myself, "Man! That is quiet. I wonder if something is wrong."

In Chairgun the time of flight works out to 357 ms at 85 yards. The temperature today was around 50 degrees F and I am at sea level so the speed of sound was real close to 1100 fps. It takes 232 ms for sound to travel 85 yards under those conditions. We can use this information to calculate that the sound of the shot should arrive at the target about 125 ms before the pellet does. So if we look at the time line we can identify the actual sound of the shot and calculate the power of that impulse.

Here is a shot being fired so that the pellet passes over the microphone and strikes a bush about 20 feet behind it. Play it at half speed.

You will notice that you do not hear the sound of the shot, just the zip of the pellet passing over the microphone.
I have reduced the speed to 25% in this next cut of the sample. You can just hear the sound of the shot at the beginning of the "zzziiiiippppp" sound. If you slow this cut to half speed you will be listening to the actual sound at 1/8th speed. You can clearly hear the shot but hey... ain't nobody gonna hear that unless they are listening for it with a "Big Ear".

Here is the graph of that sound from Audacity.

 

[Loren]

Pretty cool!

 

[LDP]

I can hear the shot in the first clip pretty clear. More important than if a recording catches the shot, does a person standing 80 yds away hear it and if they do how loud is it to them. Does it make enough noise to draw attention to it. I have sat 40 yds down range from my pcp rifles to see how the shot sounds to me when I test my mod designs. I had a couple designs that I thought were performing about the same when I was the shooter. When I was 40 yds down range It was very clear which designs were superior.

 

[OldSpook]

I can hear the shot in the first clip pretty clear. More important than if a recording catches the shot, does a person standing 80 yds away hear it and if they do how loud is it to them.

That's why I use meters. The meter doesn't lie or get confused.

Does it make enough noise to draw attention to it.

It does if it is 10 dB above the noise floor and lasts a couple hundred milliseconds, yes. That signal is perhaps 10 or 15 ms at about 8 kHz. It is unlikely that even you would hear it unless the pellet whizzed past you to get your attention. Hence the need for the pellet to pass near the sensor, to place the marker to find the shot.

I have sat 40 yds down range from my pcp rifles to see how the shot sounds to me when I test my mod designs. I had a couple designs that I thought were performing about the same when I was the shooter. When I was 40 yds down range It was very clear which designs were superior.

There is little doubt someone with good hearing will be able to pick that up if they are paying attention. That is to say if they are listening for it they would probably notice it. If they were not you could probably fire ten shots without them ever noticing so long as there wasn't some other noise that got them to start listening. It is EASY to hear something you ARE listening for...

At -45dB that signal is almost 20 dB above the noise floor (-64 dB). You convert that by adding 90 IIRC. So 45 dB with a noise floor of about 25 dB. It takes about 10 dB above the noise floor for about 200 ms to get someone's attention so at 20 dB the signal would need to last about 100 ms and likely would need to be repeated before someone otherwise engaged would take notice. Lift that noise floor with a bit of a breeze and the signal drops right down into it. IOW this experiment doesn't work if there is a breeze, if you are in town and not in the country or if your wife is telling you to pay attention....

https://danumbs.co.uk/wp-content/uploads/2021/02/decibel-chart-800x795-2-768x763.jpg

That microphone can pick up the sound of the trigger on that rifle being pulled at ten yards. That loud slap you are hearing at the end of the clip is the pellet hitting brush about 25 feet behind the microphone. The whiz you are hearing is the sound of the pellet passing over the microphone. Neither of those are very loud. See the chart above.

 

[Dr. Kralenstein]

IME, even if you have a super quiet gun, if there isn't any background noise, you're going to hear the gun to a certain degree. During winter time things are much louder since no foliage to absorb or deflect sound, and also colder/denser air amplifies the sound.

It's much less alarming when you have a good moderator that eliminates the pop of the muzzle. I've yet to see any pellet rifle that is dead silent, regardless of the muzzle report. The mechanical action of the gun will make noise. Maybe hammerless designs are quiet, I wouldn't know. Never seen one in the wild yet.

 

[OldSpook]

IME, even if you have a super quiet gun, if there isn't any background noise, you're going to hear the gun to a certain degree. During winter time things are much louder since no foliage to absorb or deflect sound, and also colder/denser air amplifies the sound.

It's much less alarming when you have a good moderator that eliminates the pop of the muzzle. I've yet to see any pellet rifle that is dead silent, regardless of the muzzle report. The mechanical action of the gun will make noise. Maybe hammerless designs are quiet, I wouldn't know. Never seen one in the wild yet.

Absolutely, there is no such thing as "mouse fart quiet" any gun that is shooting around 66 dB is EXCEPTIONALLY quiet, maybe 2 or 3 percent of the gun/moderator combinations I've tested are that quiet.

A hammer-less design would probably be quieter, yes, I suppose.

Silencing is about "Range to Noise Floor" or "Detectable Range". See this post.

 

[LDP]

There is little doubt someone with good hearing will be able to pick that up if they are paying attention. That is to say if they are listening for it they would probably notice it. If they were not you could probably fire ten shots without them ever noticing so long as there wasn't some other noise that got them to start listening. It is EASY to hear something you ARE listening for...

Yes and thats why I like to hear how my mods sound to my ear. If its almost undetectable to me when I know whats making the noise it wont get any attention from anything else at 40 yds or further. I can shoot firearms on my property and I dont have to worry about a neighbor hearing any gun shots and raising a fuss cause I simply dont care since I am legal to shoot. So my noise concern comes down to spooking the critters I am targeting. Once the noise level drops to a certain point theres no reaction to the shot allowing for multiple targets or a follow up if the shot misses. Thats my goal when I make a mod and so far I have been successful on my test rifles.

 

[OldSpook]

Yes and thats why I like to hear how my mods sound to my ear. If its almost undetectable to me when I know whats making the noise it wont get any attention from anything else at 40 yds or further. I can shoot firearms on my property and I dont have to worry about a neighbor hearing any gun shots and raising a fuss cause I simply dont care since I am legal to shoot. So my noise concern comes down to spooking the critters I am targeting. Once the noise level drops to a certain point theres no reaction to the shot allowing for multiple targets or a follow up if the shot misses. Thats my goal when I make a mod and so far I have been successful on my test rifles.

Oh well then you would LOVE this moderator. Maybe we could swap a couple and I could test yours the same way?

 

[LDP]

Oh well then you would LOVE this moderator. Maybe we could swap a couple and I could test yours the same way?

Which mod was used in this test? Also I was wondering where people buy their carbon fiber tubing? I have a hard time finding any tubing less than $80 for a couple feet and matte finish instead of glossy. Maybe its the size I am after I want 1.5, 1.75 and 2.0 od tube sizes. Maybe thats the going rate. I guess I am used to getting aluminum tubing for $12 a foot.

 

[OldSpook]

Which mod was used in this test?

Top post for details on that moderator 40x127

Also I was wondering where people buy their carbon fiber tubing? I have a hard time finding any tubing less than $80 for a couple feet and matte finish instead of glossy. Maybe its the size I am after I want 1.5, 1.75 and 2.0 od tube sizes. Maybe thats the going rate. I guess I am used to getting aluminum tubing for $12 a foot.

Yeah it is expensive. I've never seen it in imperial units all I've ever seen is in millimeters. So I just do all my work in millimeters except for the helicoils.

Let me know if you want one tested. No worries I won't keep it

 

[Mr.H]

Which mod was used in this test? Also I was wondering where people buy their carbon fiber tubing? I have a hard time finding any tubing less than $80 for a couple feet and matte finish instead of glossy. Maybe its the size I am after I want 1.5, 1.75 and 2.0 od tube sizes. Maybe thats the going rate. I guess I am used to getting aluminum tubing for $12 a foot.

Have you looked on eBay? I think I might have a link on my phone, I'll update later..

Here is one listing: https://www.ebay.com/itm/325769892425

 

[lbc_PSI]

Which mod was used in this test? Also I was wondering where people buy their carbon fiber tubing? I have a hard time finding any tubing less than $80 for a couple feet and matte finish instead of glossy. Maybe its the size I am after I want 1.5, 1.75 and 2.0 od tube sizes. Maybe thats the going rate. I guess I am used to getting aluminum tubing for $12 a foot.

Tons of carbon fiber tubing on Amazon. If you don’t like the “glossy” finish, a light rub with a “magic eraser” takes the shine off.

 

[124nut]

Just for giggles, today after I got back from a Squirrel hunt I decided to see what my Talon P sounded like at 100 yards. The gun is running a moderator design I call the "Krait". The moderator is 40mm x 127mm and is for all practical purposes an enlarged "Ember" which we have had so much success with.

I expected I'd be able to show that the gun was almost undetectable at 100 yards. I got out the LASER and went next door to shoot thinking the yard there was 100 yards long but it wasn't it was 85 yards so I ran with that. A little math and I'd be able to talk about the noise level of the gun at 100 yards, or so I thought.

The gun is shooting JSB 15.89s at 800 fps. I tweaked the tune a bit yesterday and reduced the muzzle energy from 26 fpe to about 22 fpe. I noticed it quieted the gun some. Today when I was hunting I took a couple of practice shots and thought to myself, "Man! That is quiet. I wonder if something is wrong."

In Chairgun the time of flight works out to 357 ms at 85 yards. The temperature today was around 50 degrees F and I am at sea level so the speed of sound was real close to 1100 fps. It takes 232 ms for sound to travel 85 yards under those conditions. We can use this information to calculate that the sound of the shot should arrive at the target about 125 ms before the pellet does. So if we look at the time line we can identify the actual sound of the shot and calculate the power of that impulse.

Here is a shot being fired so that the pellet passes over the microphone and strikes a bush about 20 feet behind it. Play it at half speed.
View attachment 436290
You will notice that you do not hear the sound of the shot, just the zip of the pellet passing over the microphone.
I have reduced the speed to 25% in this next cut of the sample. You can just hear the sound of the shot at the beginning of the "zzziiiiippppp" sound. If you slow this cut to half speed you will be listening to the actual sound at 1/8th speed. You can clearly hear the shot but hey... ain't nobody gonna hear that unless they are listening for it with a "Big Ear".
View attachment 436292

Here is the graph of that sound from Audacity.
View attachment 436291

I'd like to buy a mod from you but I can't PM you. Is there any other way I could buy one. Thanks, Gary

 

[OldSpook]

I'd like to buy a mod from you but I can't PM you. Is there any other way I could buy one. Thanks, Gary

I don't do "special orders" for the moderators I build. I'm not really in the business of selling moderators. I am experimenting and taking orders gets in the way of that process. What I do is list moderators in the classifieds which turned out well, which have been tested and which have brought a smile to the faces of the guys who shoot them. I build them and then I list them in the classifieds after I am done experimenting with them. If it is listed as "used" it is one of those.

Sometimes when I need supplies I build a lot of three or four tried and true tested models which I KNOW work well and put them up in the classifieds. The "Ember" is one such design. Those are no longer in testing. If you see me list any of those in the classifieds they are listed as "new".

Thanks for asking. I am sorry it took so long to get back to you on this but I've been on range master detail all day at our local PB range.

Regarding the ability PM other members, the rules you read when you signed up for the forum addressed that issue. You need ten posts, a couple more and you will be home free. Then you can advertise in the classifieds and PM other members.

HTH
Mike

 

[LDP]

Tons of carbon fiber tubing on Amazon. If you don’t like the “glossy” finish, a light rub with a “magic eraser” takes the shine off.

I did another search on amazon and found the sizes I wanted. Not terrible priced either. I must have been tired the first time I searched Thanks again for the replies and tip about removing the shine. Back to the scheduled programming.

 

[denovich]

search for melamine sponge if you want to find the non-branded ones