Suppressed 22 breaking the sound barrier

[jwh20]

yeah, I got a couple 50 round boxes of that ammo and it shot great, but I can't consistently find it in stock

Nor can I. In fact I originally bought this because it's all I could find. But it turns out it's great for target shooting and for taking out varmints. They don't know what hit 'em and if there are more than one in the yard, it's so quiet that it rarely spooks the others.

 

[Force10]

A while back before I got my suppressor, a buddy of mine got me a thousand rounds of CCI "standard" velocity (1080 fps). I burned through most of it plinking, but used some with the suppressor, man it's sweet through my FV-SR.

RE: What affects speed of sound
I was researching this the other night. It has been indicated above that as temps decrease the speed of sound decreases, making ammo that is in the trans-sonic range liable to go super-sonic. How does humidity affect the speed of sound? My understanding is that as humidity increases the speed of sound increases, but I could be wrong. What is the *ideal* weather for quiet shooting with "standard" velocity ammo?

 

[jwh20]

Higher relative humidity increases the speed of sound. So a cold moist day would give you the best conditions for keeping your shots in the subsonic range. But standard velocity .22 LR ammo, which I believe is well over 1200 fps is not going to be subsonic under and conditions you're going to be wanting to be shooting in.

 

[mdmayo]

Not the case. It will DECELERATE more rapidly than in warmer/thinner air but it's initial velocity will be about the same. How far does a bullet need to travel at supersonic speed to generate a "crack"? I'm not sure but likely only a short distance.

Interesting theory on the temperature of the powder but I'm quite skeptical. Can you cite any actual research or testing on that topic? Considering how small the amount of powder in a .22 LR is and considering the high-temperature at which smokeless powder burns, I think you'll find the initial temperature of the powder is insignificant.

^^^^ this

 

[jwh20]

Google "BLC-2 temperature sensitivity" or read any reloading book.

I did that and found some mostly anecdotal stories but all were with large-case rifle cartridges. I didn't see anything having to do with .22LR loads. Typically a .22LR has only a very small amount of powder and it burns very quickly unlike a large case where you have a relatively much longer burn time.

I'm sure that there is a temperature effect in .22LR, but I'm not convinced that it is all that significant.

I'll put this in my list of things to do when I'm bored and can chrono some batches of .22LR which have been chilled or warmed to various temperatures.

 

[Hornett]

The Remington subsonic work well for me, but they tend to jam every now and then.

 

[Ahburns]

I had an interesting experience with The Remington subsonic. They are barely subsonic, around 1050fps, in my ruger american with an 18 inch barrel. When I put the suppressor on they break the sound barrier producing a crack, which is louder than shooting suppressed.

 

[gewehr3]

I have found the Remington Subsonic rounds to be inconsistent, especially recent production.

 

[rotortech]

Can we make a conclusion that shooting 22LR out of a rifle with a silencer will probably NOT be subsonic? Unless you find some very low velocity ammo for that purpose.

 

[avboiler11]

Can we make a conclusion that shooting 22LR out of a rifle with a silencer will probably NOT be subsonic? Unless you find some very low velocity ammo for that purpose.

Never had CCI SV go super through a 16 or 18" 22LR with can...

 

[M67]

Never had CCI SV go super through a 16 or 18" 22LR with can...

Same with Federal Target. Most of the decent-entry level quality target standard velocity loads I've shot will remain subsonic.

I said decent-entry, so that kind of rules out anything Remington

 

[engineerpower]

To clear things up a bit:

Cold air: speed of sound UP
Hot air: speed of sound DOWN
Moist air: speed of sound UP
Dry air: speed of sound DOWN
Warm powder: pressure and bullet velocity UP
Cold powder: pressure and bullet velocity DOWN

The speed of sound is based on the ability of molecules in air to transmit energy in the form of vibrational energy. The more dense the molecules, the better and faster they are able to transmit energy. This is why sound travels so fast in water, and why "In space no one can hear you scream"...

 

[Beowulf]

To clear things up a bit:

Cold air: speed of sound UP
Hot air: speed of sound DOWN
Moist air: speed of sound UP
Dry air: speed of sound DOWN
Warm powder: pressure and bullet velocity UP
Cold powder: pressure and bullet velocity DOWN

The speed of sound is based on the ability of molecules in air to transmit energy in the form of vibrational energy. The more dense the molecules, the better and faster they are able to transmit energy. This is why sound travels so fast in water, and why "In space no one can hear you scream"...

So if I shoot my suppressors on a cold, moist day, after keeping my ammo in the freezer overnight, I can get them to sound like they do in Hollywood movies?

 

[engineerpower]

Only in post...

 

[AmmoManAaron]

To clear things up a bit:

Cold air: speed of sound UP
Hot air: speed of sound DOWN
Moist air: speed of sound UP
Dry air: speed of sound DOWN
Warm powder: pressure and bullet velocity UP
Cold powder: pressure and bullet velocity DOWN

The speed of sound is based on the ability of molecules in air to transmit energy in the form of vibrational energy. The more dense the molecules, the better and faster they are able to transmit energy. This is why sound travels so fast in water, and why "In space no one can hear you scream"...

This is generally true, but it's worth noting that a few powders behave the opposite of this. Hodgdon Lil'Gun and especially Alliant 410. This is why Alliant has not released any handgun data for 410, even though it has approximately the same burn rate as 2400 when used in magnum handgun cartridges. A .44 Magnum load using 410 that is safe in the Spring and Summer will be both erratic and overpressure during cold Winter weather - bad mojo for sure! Sorry for the but I thought this was an exception worth sharing since it might help keep somebody safe (considering the ongoing powder shortage and everything that goes with that).

 

[lovemywoods]

My comments in blue.

To clear things up a bit:

Cold air: speed of sound [STRIKE]UP [/STRIKE] DOWN
Hot air: speed of sound [STRIKE]DOWN[/STRIKE] UP
Ref: Speed of Sound
For a round to be sub-sonic, it must travel below the speed of sound for the current conditions. Therefore, it is easier for a bullet to be subsonic in the summer.


Moist air: speed of sound UP True. However, the affect is about 0.35% faster from 0 to 100 degrees F. Very small. Moist air is less dense than dry air since water molecules are lighter than the nitrogen and oxygen molecules they displace.
How Does Humidity Affect Speed of Sound? | Science - Opposing Views
Dry air: speed of sound DOWN


Warm powder: pressure and bullet velocity UP
Cold powder: pressure and bullet velocity DOWN


The speed of sound is based on the ability of molecules in air to transmit energy in the form of vibrational energy. [STRIKE]The more dense the molecules, the better and faster they are able to transmit energy.[/STRIKE] This is why sound travels so fast in water, and why "In space no one can hear you scream"...

At the temperatures we live in, air density doesn't change much. Molecules in a gas are incredibly far apart. The air molecules do become more energetic with rising temperatures and will transmit sound (pressure waves) faster.

So if I shoot my suppressors on a [STRIKE]cold,[/STRIKE] hot, moist day, after keeping my ammo in the freezer overnight, I can get them to sound like they do in Hollywood movies?

Probably not.

 

[engineerpower]

My mistake, remembered the inverse formula from my aeronautics courses: Mach numbers decrease with temperature, rather than speed of sound.

Here are the corrected relationships:

Cold air: speed of sound DOWN
Hot air: speed of sound UP
Moist air: speed of sound UP
Dry air: speed of sound DOWN
Warm powder: pressure and bullet velocity UP
Cold powder: pressure and bullet velocity DOWN

Air density does change at our temperatures, that's why it has to be included in ballistics calculations (air resistance). It doesn't affect the speed of sound because the relationship of air pressure and density are inversely related in an open atmospheric condition, and cancel the effect of each other out.

 

[lovemywoods]

Air density does change at our temperatures, that's why it has to be included in ballistics calculations (air resistance). It doesn't affect the speed of sound because the relationship of air pressure and density are inversely related in an open atmospheric condition, and cancel the effect of each other out.

I love it when you talk nerdy to me!

 

[HamsterStyle]

Dave, this could possibly explain why my Ruger American Rimfire was a bit louder than I explained when we tested it out Saturday. The first time I shot it, it was around 70 degrees, making it insanely quiet. At your house, it was closer to 50 degrees. We must have crossed that threshold to make it noisier. Maybe. it was still fun though.