Change in Sound of Gunfire

[Target_Liberty]

I did some shooting with friends and family yesterday. We were shooting along when all of a sudden the gun shots got remarkably louder in an instance on the 10/22 we were shooting. Enough so that the 5 of us noticed it at the same time. It also sounded more like a crackling sound. We grabbed a different box of ammo and even a different 10/22 and were still getting the same sound.

The thing we could think of was the humidity. It felt like it was going to rain. Has anyone experienced something like this?

 

[92G]

Possibly bolt wasnt fully closed, ie slightly out of battery....that can cause different sound.

 

[Varmint]

denser air will carry that sound better, you're probably right about humidity as the cause.

 

[Wrench75]

Possibly bolt wasnt fully closed, ie slightly out of battery....that can cause different sound.

He said they tried different guns with the same result, so it is doubtful that was the problem.

Humidity seems like a possibility. Or maybe a change in the wind direction. Can't say I have experienced this personally.

 

[pepperoni]

Could be many factors.
Temperature and humidity do play a role, but usually at greater distances to be discerned.
The speed of sound is raised by humidity. The difference between 0% and 100% humidity is about 1.5 m/s at standard pressure and temperature, but the size of the humidity effect increases dramatically with temperature.
So.. the humidity raised and the temperature dropped while you were at the range and, wala your ears picked it up.
Im guessing, actually i dont have the slightest clue, i just google fued the crap out of speed of sound

http://en.wikipedia.org/wiki/Speed_of_sound#Dependence_on_the_properties_of_the_medium
http://www.sengpielaudio.com/calculator-airpressure.htm

 

[white feather]

As stated earlier, as temperature goes down, the speed of sound goes down. As relative humidity goes down, the speed of sound goes up (but relative humidity has a much smaller effect than temperature). The cracking noise that you heard is produced by the bullet breaking the sound barrier as it exits the muzzle. What ammo were you using? CCI standard velocity .22 ammo has a (nominal) velocity of 1070 ft/sec (subsonic). It should be supersonic until the temperature goes below 32 degrees F (which is unlikely on a summer day). If it got really cold, the standard velocity would break the sound barrier and make a cracking noise. CCI high velocity is listed at 1215 ft/sec it is supersonic up to about 154 degrees F but that would be cracking noise to no cracking noise and while it was hot yesterday, it was not that hot...
White Feather

 

[Spanz]

its aliens

 

[smokey-seven]

Distance to the berm and range you were shooting?

A wind / humidity / temperature shift with faster than sound ammo on a short range to the berm gives you a report on the sonic speed break bouncing back from the berm. You get two reports, one of the detonation and one of the faster than sound echo. It is also NOT uncommon to get different speeds in the same brand/box of ammo.

 

[Wrench75]

You get two reports, one of the detonation and one of the faster than sound echo. I

Is there something crazy in my head? Or did you just say that the echo, a sound, is traveling faster than the speed of sound?

 

[Target_Liberty]

It was 80 degrees. I'm not good at distance but it was relatively short, maybe a 100ft. We were shooting CCI brand ammo with a 1050 but FPS switched to a Centurion at 1250 FPS and got the same effect.

 

[KilgoreTrout]

Sound travels faster in humid air. The dew point was in the 70's at my house yesterday. Soupy. I could hear the chime of a church clock 5 miles from me. Can't hear it most days unless it's humid or raining.

 

[Kevin_NH]

A little sparrow told me... quiet is good!

The cracking noise that you heard is produced by the bullet breaking the sound barrier as it exits the muzzle. What ammo were you using? CCI standard velocity .22 ammo has a (nominal) velocity of 1070 ft/sec (subsonic).

I believe you're on the right track.

If for some reason, all their early shots were subsonic, the perceived noise would be considerably quieter. Then all the later shots were supersonic, thus the cracking sound.

Or this is fate telling the OP that he needs to get suppressors to upgrade those 10/22s.

 

[not new guy]

As relative humidity goes down, the speed of sound goes up (but relative humidity has a much smaller effect than temperature).

Sound travels faster in humid air. The dew point was in the 70's at my house yesterday. Soupy. I could hear the chime of a church clock 5 miles from me. Can't hear it most days unless it's humid or raining.

Point, to KilgoreTrout.

http://en.wikipedia.org/wiki/Speed_of_sound

Humidity has a small but measurable effect on sound speed (causing it to increase by about 0.1%-0.6%), because oxygen and nitrogen molecules of the air are replaced by lighter molecules of water. This is a simple mixing effect.

 

[tuna]

Did you take off your ear protection?

 

[Ink]

Did everyone replace the batteries in their ear pro at the same time mayhaps?

 

[white feather]

Point, to KilgoreTrout.

http://en.wikipedia.org/wiki/Speed_of_sound

My bad, I got the down and up backwards on humidity... [sad2] Temp down speed down. Humidity up speed up. I wanted to make the humidity change in the same direction as temperature and forgot to switch the speed. Oops.

It was 80 degrees. I'm not good at distance but it was relatively short, maybe a 100ft. We were shooting CCI brand ammo with a 1050 but FPS switched to a Centurion at 1250 FPS and got the same effect.

The Centurion should have made a crack as it is supersonic. The CCI should not have made a crack.
White Feather

 

[smokey-seven]

Is there something crazy in my head? Or did you just say that the echo, a sound, is traveling faster than the speed of sound?

One does not hear the sonic wave from behind it, the report masks it as they happen too close in time. You will hear the return of it as an echo off a distant solid point as well as the report. No it comes in as a single sound AFTER the report, the report being the firing of the ammo. Find someplace where there is an echo and clap your hands. You hear the original clap and then the echo. Same thing.

Ball parking your stated distance, at roughly 200 feet (downrange and back), the report and sonic echo should return in less than 2 tenths of a second.

 

[FalArAk]

Is there something crazy in my head? Or did you just say that the echo, a sound, is traveling faster than the speed of sound?

Maybe he is on to something.