❓ Acoustics Question: Projectile Flight Noise 𐃘 How to keep it down?

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JungleShooter

JungleShooter

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❓ Acoustics Question: Projectile Flight Noise 𐃘 How to keep it down? ​



For a good while now, I am trying to reduce the noise that my shooting causes.

I've looked at the following:

🔵 Discharge Noise
➠ Eliminate spring guns.


🔵 Muzzle Noise
➠ Use lower power (of course, that's a given).
➠ Use a silencer, that is both long and has a large volume and small passage ways.
➠ Tune for a shorter sip of air that is at a higher regulator pressure (e.g., 8% below the max. on the power curve is better than 2%).


🔵 Impact Noise
➠ Avoid paper and cardboard targets. Instead use some type of synthetic/ plastic sheets and draw bulls on those.
➠ Soften the impact using rubber mulch or similar filler material. This is primarily for target shooting, but can also be done for shots on quarry if they often show up at the same places (e.g. a bait station).
➠ On quarry: Use slower impact velocities, smaller calibers, and projectiles that enter the flesh smoothly (pointed heads, or domes, rather than wadcutters and hollow points).



🔴 Projectile Flight Noise
That's a new one to me!
Twice now people have been telling me at private shooting ranges that they could hear the flight of the projectile wizzing by!

❓ Here are my questions:

➊ What's quieter? Slugs or diabolo pellets?
¿Domed pellets or hollow point pellets

➋ What's quieter? Faster or slower projectiles? (below the speed of sound, that is)

➌ Is there an ideal quiet velocity — for either slugs or pellets?


For example: I wonder if the whizzing noise of my projectile would be less it I shot a .22cal pellet at 30FPE, or a .30cal pellet at 30FPE, or a .22cal slug at 40FPE?


Thanks for any input you might have! Physics was never my strong suit — I barely passed it....🤦🏻‍♂️

Matthias 😊
 
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your post this time was as good and thorough as your last long one.. very nice!! thank you .
I'll comment on what I think your title and last point said..
flight noise.. I didn't even make physics so no knowledge there and if I did do physics it must have all fell out of the other ear🤣
first..if it's flying it's going to make noise.. yes I have heard real love bullets flying past my head when I was riding my horse and came across poachers once and took close to I suppose a marijuana grow? I don't know..
solution is simple.. no projectile flight= no noise..
another one I heard is keep you head down 🤔 no I don't think you are guilty of shooting that close to anyone..
on the funny side.. shoot steel gongs.. much more fun!
I'd likely buy firebird targets, but I won't spend a dollar on paper target so not a chance for firebird targets.. I'm too poor..
yes it's always quieter if below the speed of sound.. which you stated.. and I prefer it that way although assuming that I don't know if any difference in sound between Springer and PCP.. assuming PCP is well set, of actually consider the Springer quieter even a magnum.. like a Diana 34 in 177 vs d48 in 22.. about the same but I think the d48 was quieter, definitely more accurate because when I shoot, I shoot..wind or not..
I think the d48 in 177 would be definitely louder than 22 unless you use jsb beasts to keep it subsonic..
I'll write more later and follow this thread..
t
I just remembered the last one I read you wrote.. what is the best airgun for my application..
myself I hope it's the one that is showing up Monday..
if not is it ok to PM you, I have very specifics, know what I want and don't want.. but might be guns I'm overlooking that are the one..
thank you for writing such great post
Mark
 
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I think in the end it’s fairly simple. The faster they go to louder they’ll be. I once had my u2 shooting slugs at 1080fps. The loudest part of a shot was the slug passing maybe 1-2 yards past my wood stacks (target box behind the wood stacks). Once I had them down to 1030 the crack from passing the wood stacks went away. The projectile traveling will push a wave of air which translates to sound. The more pressure behind that wave (faster projectile), the louder it’ll be. For domed vs slugs vs HP, I don’t think it makes much of a difference to the human ear to be honest. It’s a pebble of lead pushing through the air… but then, you learn something new every day I guess so open to others with more knowledge chiming in!
 
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markhooper said:
your post this time was as good and thorough as your last long one.. very nice!! thank you .
I'll comment on what I think your title and last point said..
flight noise.. I didn't even make physics so no knowledge there and if I did do physics it must have all fell out of the other ear🤣
first..if it's flying it's going to make noise.. yes I have heard real love bullets flying past my head when I was riding my horse and came across poachers once and took close to I suppose a marijuana grow? I don't know..
solution is simple.. no projectile flight= no noise..
another one I heard is keep you head down 🤔 no I don't think you are guilty of shooting that close to anyone..
on the funny side.. shoot steel gongs.. much more fun!
I'd likely buy firebird targets, but I won't spend a dollar on paper target so not a chance for firebird targets.. I'm too poor..
yes it's always quieter if below the speed of sound.. which you stated.. and I prefer it that way although assuming that I don't know if any difference in sound between Springer and PCP.. assuming PCP is well set, of actually consider the Springer quieter even a magnum.. like a Diana 34 in 177 vs d48 in 22.. about the same but I think the d48 was quieter, definitely more accurate because when I shoot, I shoot..wind or not..
I think the d48 in 177 would be definitely louder than 22 unless you use jsb beasts to keep it subsonic..
I'll write more later and follow this thread..
t
I just remembered the last one I read you wrote.. what is the best airgun for my application..
myself I hope it's the one that is showing up Monday..
if not is it ok to PM you, I have very specifics, know what I want and don't want.. but might be guns I'm overlooking that are the one..
thank you for writing such great post
Mark
Click to expand...


Thank you, Mark, for your kind reply! 😊
That was very nice of you!! 🤝🏼


Of course you can PM me. 👍🏼(Sometime, life get's in the way of our hobby, but I am usually attentive to PM's.)



I hope the gun showing up at your door this Monday will satisfy your expectations!

Have a great Sunday,

Matthias
 
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greenbeans said:
I think in the end it’s fairly simple. The faster they go to louder they’ll be. I once had my u2 shooting slugs at 1080fps. The loudest part of a shot was the slug passing maybe 1-2 yards past my wood stacks (target box behind the wood stacks). Once I had them down to 1030 the crack from passing the wood stacks went away. The projectile traveling will push a wave of air which translates to sound. The more pressure behind that wave (faster projectile), the louder it’ll be. For domed vs slugs vs HP, I don’t think it makes much of a difference to the human ear to be honest. It’s a pebble of lead pushing through the air… but then, you learn something new every day I guess so open to others with more knowledge chiming in!
Click to expand...
Stand behind cover down range and have somebody shoot past you. I'd done this with powder burners but did not expect what I heard from pellets and slugs with air rifles.
 
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JungleShooter said:
Thank you, Mark, for your kind reply! 😊
That was very nice of you!! 🤝🏼


Of course you can PM me. 👍🏼(Sometime, life get's in the way of our hobby, but I am usually attentive to PM's.)



I hope the gun showing up at your door this Monday will satisfy your expectations!

Have a great Sunday,

Matthias
Click to expand...
thank you,I understand life gets in the way.. I've been in AGN but it's probably been a month since I target shot, just hazing turkey out of the garden don't count.. unfortunately life getting in the way for me was major health issues.. I've got a temporary bandaid that has made it 100% better now thanks to my doctor, but it's a bandaid, not the solution.. grateful for whatever help I receive.

your very lengthy and thorough post's are some of my favorite reading materials..
thank you so much 👍
Mark
 
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6gun said:
Stand behind cover down range and have somebody shoot past you. I'd done this with powder burners but did not expect what I heard from pellets and slugs with air rifles.
Click to expand...
wished I could have done that when shot at on horseback, but I put it in high gear and went down a trail in case they had a 4x4 🤣🤣
Mark
 
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markhooper said:
wished I could have done that when shot at on horseback, but I put it in high gear and went down a trail in case they had a 4x4 🤣🤣
Mark
Click to expand...
No cover isn't fun, I've been there too once(thank God) . Club shooting I would run the moving target from behind a berm and you learn a lot about what each bullet caliber and size sounds like for supersonic powder burners

Airguns I was suffering an accuracy issue on the day I'm shooting at my buddies, he's across property feeding animals and tells me it's sonic cracking down range, well sort of. It was just on the edge of sonic and making noise for the neighbors I didnt want with these slippery slugs.

We lowered velocity and tried others for science. Pellets are loud at the top of their sub sonic range. It's a real eye opener when we thought we were being sneaky. Hunting tactics have changed now due to this
 
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Tumblinginflight said:
So many competing variables. Pure hypothesis, but I would think gyroscopically stabilized would beat drag stabilized projectiles, and that the highest ballistic coefficient would win the quietness game.
Click to expand...
In addition to this, the faster the twist, the more it's gonna buzz in the air...

So... a high bc projectile , going slow, at a slow twist rate, should be the quietest...

Also, again intuitively, the more air it displaces (caliber size), the more noise...

That makes a high bc 177, going slow, with slow twist rate, being the likeliest candidate for quietest... is this even possible ?

Just my thoughts ... no actual testing... 😉

Bob
 
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Interesting topic. Thinking that some testing is in order. I know that clay pigeons hiss as they go by, but never really thought about pellets. It'll be easy enough to set up a recorder down range and send different pellets by it. Audio editing freeware (like Audacity) will serve to isolate the sound.

Cheers,

J~
 
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JungleShooter said:

❓ Acoustics Question: Projectile Flight Noise 𐃘 How to keep it down?…​




🔴 Projectile Flight Noise
That's a new one to me!
Twice now people have been telling me at private shooting ranges that they could hear the flight of the projectile wizzing by!…



Matthias 😊
Click to expand...

@JungleShooter Where on earth are these people situated to hear your projectiles whizzing past them? How are these people situated shooting lanes arranged? In my mind I can’t conceive how this would even occur In a safe environment.
 
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Tumblinginflight said:
So many competing variables. Pure hypothesis, but I would think gyroscopically stabilized would beat drag stabilized projectiles, and that the highest ballistic coefficient would win the quietness game.
Click to expand...
questions.. big words stupid me.. so I hope just a clear answer. you mentioned gyro vs drag.. so which is the pellet and which is the slugs?
Mark
 
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6gun said:
No cover isn't fun, I've been there too once(thank God) . Club shooting I would run the moving target from behind a berm and you learn a lot about what each bullet caliber and size sounds like for supersonic powder burners

Airguns I was suffering an accuracy issue on the day I'm shooting at my buddies, he's across property feeding animals and tells me it's sonic cracking down range, well sort of. It was just on the edge of sonic and making noise for the neighbors I didnt want with these slippery slugs.

We lowered velocity and tried others for science. Pellets are loud at the top of their sub sonic range. It's a real eye opener when we thought we were being sneaky. Hunting tactics have changed now due to this
Click to expand...
yes but at least they were not purposely aiming at you..umm with im assuming AK 47 and full auto burst 🤔.. yes let's disappear into the woods..
Mark
 
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markhooper said:
Tumblinginflight said:
So many competing variables. Pure hypothesis, but I would think gyroscopically stabilized would beat drag stabilized projectiles, and that the highest ballistic coefficient would win the quietness game.
Click to expand...

questions.. big words stupid me.. so I hope just a clear answer. you mentioned gyro vs drag.. so which is the pellet and which is the slugs?
Mark
Click to expand...
@markhooper Gyroscopically stable = stabilized by spinning. This refers to slugs.

Pellets are stabilized by drag as air moves across and around the pellet’s skirt.

This is my understanding.
 
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