Suppressed 22 breaking the sound barrier

[mj.elder]

Looking for some knowledge. I have a Huntertown Arms 22 suppressor. I run it on a Sig Mosquito as well as a 10/22 takedown. I seem to have a problem with much of my standard velocity and subsonic ammo giving off that "CRACK" when it breaks the sound barrier. I have read that height above sea level as well as temperature can effect this.

Does anyone else have this problem?

What can I do to keep this from happening.

What are the ideal situations (weather, pressure, altitude) for shooting 22 subsonic.

Any other knowledge would be greatly appreciated as well.

 

[jwh20]

If it's cracking then it's not subsonic even if it's labelled as such. Of course the actual speed of sound varies quite a bit depending on temperature, altitude, barometric pressure, and humidity, so what is subsonic one day at 75F may not be on a 35F day.

You don't know for sure what velocity your ammo and gun is giving you without measuring it. But you might try a different brand of subsonic 22 ammo. But I think you'll find that none of the "standard" .22LR ammo is anywhere close to subsonic.

BTW, the suppressor does not affect the velocity much if at all. But you are correct that it does not affect the "crack" if the bullet goes supersonic.

 

[mj.elder]

Right, I've had the suppressor for a couple years now and have really just had problems finding good sub ammo.

The speed of sound is 1,100 fps. Most standard velocity ammo that I have (remington gold bullet, cci standard, federal) is all measured at 1070 and 1085 fps.

I assume that this ammo is manufactured within max allowed specs and that it might vary from 1050-1125 fps, but i should be getting at least a third of them at the stated 1070 fps. But every single time every single one of them breaks the sound barrier.

I know the suppressor has little to no effect on the velocity, it is just there to collect gasses and reduce muzzle flash and volume.

I feel like some of my ammo should be functioning properly and not breaking the barrier.

Does anyone know of any lower velocity ammo that is reliable? Or should I be looking for perhaps a 42 grain round?

 

[avboiler11]

Standard Velocity ammo going supersonic...from a pistol barrel?!?

 

[mj.elder]

The more I think about it the more I think I might have been mistaken on that part. For sure out of the rifle, but I think the standard shoots fine out of the pistol.

 

[wsenefeld]

The FPS they list is typically out of a 16" barrel so your ammo going 1070 fps out of a 16" should absolutely be subsonic out of a pistol.

This is why people SBR a .22 rifle down to 4.5" to keep it from breaking the sound barrier.

Air is more dense during colder weather so the velocity slows. The weather is only helping you right now.

 

[mj.elder]

^^^ good stuff. Thanks

 

[digitalrebel80]

You can use a speed of sound calculator that will tell you what the speed of sound is with the weather that you have on that day. It might explain why you are having a problem. Today it shows the speed of sound around 1080 fps.
Here is a link to the one from the NWS
Speed of Sound Calculator

 

[KLB]

You should be able to shoot just about anything out of a 22lr pistol and have it stay subsonic. I have yet to find one that goes supersonic with my MP22.

Standard Velocity CCI is subsonic. I do not know of any other "Standard Velocity" 22lr that is. Most of the manufacturers make subsonic 22lr though. I have CCI, Remington and Aguila for sure. Might even be another one down in the stash.

In my rifles all of the above subsonic ammo will stay subsonic.

 

[Rookie]

Gemtech makes subsonic. I'm running a Tactical solutions sbx on my 10/22. The nice thing about that barrel is that it is about eleven inches long which helps keep most shots subsonic. I can shoot m22 and Aquila and about 90-95% stay subsonic.

 

[jwh20]

Air is more dense during colder weather so the velocity slows. The weather is only helping you right now.

Actually the opposite is the case. Colder air is denser and that lowers the speed of sound. The formula that is used as an approximation is:

Vsound = 331.4 + 0.6 Tc

Tc is the air temperature in C and you will get m/s. So using this gives us:

1) 75F (23.8C) = 346 m/s = 1135 f/s
2) 30F (-1C) = 330 m/s = 1085 f/s

So an 1100 f/s bullet will be supersonic at 30F but subsonic at 75F.

 

[mdmayo]

Air is more dense during colder weather so the velocity slows. The weather is only helping you right now.

As temperature decreases, so does the speed of sound. Your premise is flawed.

 

[lovemywoods]

Here's a graph of the speed of sound versus air temp. Other factors, like humidity, are ignored.

As others have said, the speed of sound decreases with decreasing temperature. Therefore, ammo that was subsonic in the summer, can have a sonic "crack" in cold winter air.

Several subsonic .22 ammo varieties are advertised at 1050 feet per second. That keeps you safe down to about zero degrees F. (Barrel length will affect the velocity you observe in your firearm.)

 

[KJQ6945]

I've had real good luck with the Gemtech. It's a 42gr at 1020fps. I've only had a couple go super sonic out of an 18' rifle.

 

[wsenefeld]

As temperature decreases, so does the speed of sound. Your premise is flawed.

The bullet traveling through colder/more dense air will encounter more resistance, therefore the bullet itself will travel slower.

You can also lose as much as 100 fps when comparing summer to winter. Cold powder doesn't burn as quickly. A weak load that cycles your firearm in July may not cycle in February.

 

[jwh20]

The bullet traveling through colder/more dense air will encounter more resistance, therefore the bullet itself will travel slower.

You can also lose as much as 100 fps when comparing summer to winter. Cold powder doesn't burn as quickly. A weak load that cycles your firearm in July may not cycle in February.

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.

 

[mj.elder]

It would seem that in my haste and stubborness I made an error. For some reason i was under the impression that the ammo i was shooting was 1080 fps and slower. Apparently upon further research the bricks of ammo i was shooting are actually rated at 1180 fps and 1200 fps. So I think I found my problem. I just ordered a thousand rounds of Norma USA Tac 22 rated at 1100 fps. Should be fine out of my pistol, but we will see out of the 10/22. I'm curious to see how this ammo performs in the winter as compared to how it will shoot in the summer. Perhaps since the topic is being debated so hotly here I will take some readings with a chronograph.

 

[wsenefeld]

Interesting theory on the temperature of the powder but I'm quite skeptical. Can you cite any actual research or testing on that topic?

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

 

[jwh20]

It would seem that in my haste and stubborness I made an error. For some reason i was under the impression that the ammo i was shooting was 1080 fps and slower. Apparently upon further research the bricks of ammo i was shooting are actually rated at 1180 fps and 1200 fps. So I think I found my problem. I just ordered a thousand rounds of Norma USA Tac 22 rated at 1100 fps. Should be fine out of my pistol, but we will see out of the 10/22. I'm curious to see how this ammo performs in the winter as compared to how it will shoot in the summer. Perhaps since the topic is being debated so hotly here I will take some readings with a chronograph.

That would certainly explain it. 1180 fps is not subsonic under most conditions you're likely to experience around here. I've been using these which are listed as 1050 fps from a rifle barrel. In shooting them from my rifle I can tell you they are very quiet indeed.

 

[mj.elder]

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