Velocity vs. Accuracy - Sound Barrier

[Michael Courtney]

It would take a pretty extensive test program to demonstrate the effect of transonic loading on pistol accuracy.

Actually, it's pretty easy. Sabots are available to shoot .355, .357, .40, .429, and .451 pistol bullets from inline muzzleloaders. Using a muzzleloader allows the powder charge (thus the velocity) to be tweaked in small increments, and shooting a scoped in-line from a bench removes the need for a Ransom rest. What one will see is that a load which gives 2-3 MOA at distances where the velocity remains supersonic will suddenly give markedly worse accuracy (2-4 times the angular dispersion) at distances 25-50 yards beyond the sonic transition.

Now, for most defensive pistol applications, a loss of accuracy from 3 MOA to 12 MOA is not meaningful, nor are the ranges involved. But the effect does exist and is relatively easy to study quantitatively.

Michael Courtney

 

[wbond]

I think it might matter.

The typical distance is 10m for airgun target shooting so you're definitely right on the "under 25 yards" bit. I agree 100% as this applies to airguns. I think picking the muzzle velocity is critical to airgun accuracy since the pellets are much less aerodynamic and much lighter than bullets.

I think you're probably right about very long-range handgun shooting, (well beyond 50 yards) but I wonder about typical handgun shooting (inside 50 yards). I intentionally phrased my comment in the form of a bet, rather than as a statement of fact, because I have no information to contradict you. However, my intuition, (such as it is ) backed by a total absence of commentary on this topic as it concerns centerfire handgun target shooting, still leans strongly toward it being a very small contributor.

It would make an interesting experiment. If you are going to test it, I'd suggest using a pistol caliber carbine shot over a rest in order to eliminate the issues of trying to get precision accuracy from a handgun.

While some people do not think it matters. Others do. Furthermore, tradtional target guns and ammo like the .22 LR, .32 S&W Long, many .38 Spl, and .45 ACP target loads are all subsonics. Have you ever heard of supersonic target pistol ammo designed for accuracy? Have you ever heard of a transsonic target pistol ammo? I'm not sure about supersonic, but I doubt it. I'm sure there are no transsonic target pistols or target ammo used in any markmenship competitions.

My cousin can and does put multiple shots though the same hole using my subsonic .32 Mag at 15 yards. He did that 4 times in a row 2 days ago. A guy like that can make use of all available accuracy. I can't because I'm not good enough. However, every bit helps and I need all the help I can get.

If I tested this using a carbine rifle shooting store bought pistol ammo, the test would be wrong because the carbines give much higher velocities than pistols when using the same ammo.

My arthritis and related hand problems make me no longer able to shoot supersonic guns and ammo. I'm limited to smaller caliber subsonics like .380 ACP, 9x18, and .32 Mag. I'm hoping to step up to 9mm Para, but don't know if I can or will.

Does it matter? I'm not sure, but I think so. This whole thread started because a guy wanted to know why subsonic ammo seemed more accurate than transsonic ammo. He didn't use those exact words, but he did ask about the accuracy differences. I asked about the velocity of each. It became apparent that one was subsonic and the other transonic. Maybe that has nothing to do with his situation, but it got me thinking.

Several posters think it matters based on their reloading experiences. I'm sure others think it doesn't matter. We probably won't resolve this, but it's good we are now thinking about it.

 

[T.Stahl]

To Stahl:

How does humidity figure in? Seems it would create more wind resistance and lower the speed of sound, but that's only a guess. Am I correct?

Humidity (water vapour) will change the average molar mass of the air and thereby change the gas constant of the gas mixture. Being a three-atomic gas it will also affect the average kappa (as do the other components of air). But right now I don't know in which way it will affect the speed of sound. Wind resistance (aerodynamical drag) has nothing to do with the s.o.s.

I'm not sure, but it sounds like you're saying elevation doesn't matter. Maybe I misunderstood you.

No, that's exactly what I was saying! There is no p in c=sqrt(kappa*R*T)

Both temperature and elevation matter because they affect air density, which in turn affects speed of sound. Is your entire chart based on sea level? At higher elevations the air is thinner, which I think makes the sound barrier at a higher speed.

No, only the temperature, kappa and R matter. The chart shows the speed of sound for different temperatures. It will be 1004 ftps at -40°F - at sea level near the North Pole or on top of Mount Everest.

 

[k_dawg]

In the acoustics field, Cramer's equation/derivation is generally the accepted for accounting for humidity.

Here is a good write up on it:

http://www.sengpielaudio.com/calculator-airpressure.htm

the other advantage of Cramer's equation is; if conditions of the "air" is sufficiently different, you can account for it. Such as the speed of sound in a vessel of argon.

###

In regards to the topic, between 15 and 25 yards, there is a substantial reduction in accuracy in my 9mms when shooting 115gr and 125gr in 9mm. 115+P and 147gr remains good.

 

[wbond]

To Stahl and everyone else:

FYI - many sources (including textbooks) say elevation is important to SofS. Many other sources (including textbooks) say it is NOT important. Many other sources say elevation indirectly affects SofS.

The sources I originally looked at said elevation matters. Perhaps it doesn't. However, the source quoted by Dawg shows that elevation matters a little bit, but it not signifigant. Same with humidity.

I'm now willing to concede that maybe it does not matter, or only matters a little, or only indirectly matters. Actually, I think it matters a little, but is NOT signifigant. Same with humidity. Temp is the important thing.

Elevation does NOT matter to our overall accuracy discussion because the main topic is whether SofS affects pistol accuracy at 25 yards or not.

Below are a list of sources about speed of sound and what matters. Temp matters the most. That's one thing all SofS sources agree on. That's one thing you and I agree on.

Here's a partial list of my sources (notice that they do not agree about elevation):

Speed of Sound Sources
http://www.answers.com/topic/speed-of-sound
See the Wikpedia section a little ways down the page.

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

http://www.gi.alaska.edu/ScienceForum/ASF12/1225.html

https://secure.scientificsales.com/Details.cfm?ProdID=186&category=3
This is actually an ad to sell a high end temp measuring device that measures speed of sound to determine air temp. Interesting stuff.

http://library.thinkquest.org/12228/page6.html

Pellet Gun Accuracy and Speed of Sound Sources:
http://www.beeman.com/calselect.htm

http://pyramydair.com/site/articles/velocity/

The holy grail: Handgun Accuracy and Velocity (just found this one). Here is a source about handgun target shooting that specifically says subsonic .22 LR ammo is more accurate than faster .22 LR ammo. The beauty of this article is that they are specifically referring to handgun target shooting at handgun target distances. That tends to validate my original argument that velocity matters for handgun accuracy at handgun target distances of 25 yards. I'll even go on a limb and say it likely matters at 15 yards and farther, but becomes very noticeable by 25 yards.

Then after discussing that velocity affects accuracy of .22 LR handguns, they go on to say that it affects .38 Spl and recommend slow, heavy bullets for target shooting with a .38 Spl.

While it's true they never say the SofS has anything to do with it, they do say slower and heavier is usually most accurate. I think they don't understand the SofS issues, but they have recognized their effects. Namely, they recognize that slower and heavier is more accurate. i.e. - they know subsonic handgun rounds are most accurate (even though they don't think in terms of sound barrier).

If anyone still thinks the SofS has nothing to do with handgun accuracy at handgun target distances of 25 yards or more, then I give up. It's a free country, sort of. So think what you will.

http://www.auspistol.com.au/about/howtostart.htm

I could give more sources, but I think the above are enough.

 

[wbond]

To Mr. Dawg

I loved your post. Great stuff. I experienced poor transsonic accuracy with a .40 cal handgun years ago, but a lot of people don't believe me. Their preconceptions tell them these things can't matter at 25 yards, but my experiences tell me they do.

May I recommend trying Winchester 115 gr JHP Silver Tips in your 9mm?

Winchester claims 1225 fps muzzle velocity from a 4" barrel. If true, that should be dandy for accuracy and stopping power. This is a standard pressure round.

I'm not a 9mm shooter, but this 115 gr Silver Tip looks really good to me. They also make a nice supersonic Silver Tip for the .40 cal.

There is also a good looking 9mm 110 gr JHP that claims a muzzle velocity of 1250 fps from a 4" barrel with standard pressure. If you're interested, I'll try to remember or look up what brand that is.

Of course sectional density also matters. So a sufficiently supersonic 124 gr should be a bit more accurate than a 115 gr with same velocity. In theory, the 110 gr I mentioned would be less accurate due to less sectional density (assuming similar velocity).

I think the key is to find a bullet that has a nice velocity and a nice sectional density. Ideally, I'd like to get this from a standard pressure 9mm round, but +P is an option too.

================================

On a slightly different subject. Corbon makes a .38 Spl +P that offers 110 gr JHP at 1250 fps muzzle. I think from a 4" barrel. It does 1050 fps from a 2.5" barrel. These are Corbon's claims. It appears Corbon has things well figured out for .38 Spl.

I'm sure someone will ask me, "How do you know that Corbon's velocity claims are true?". I don't know, but if they're not true, they're smart enough to lie some attractive subS and superS velocities depending on barrel length. They're also smart enough not to mention that this ammo would probably be transsonic from a 3" barrel. They're either smart loaders or smart liers. ;-)

I like 3" barrel Rugers and Taurus revolvers, which would probably make that Corbon load transsonic. Darn. For a 3" barrel 38 Spl, 1050 fps muzzle velocity with a heavier bullet is probably best.

I think +P is fine for Ruger .38s because they can handle it all the time easily.

 

[wbond]

If they're fired a hair above speed of sound...

To Michael Courtney and all Reloaders (a challenge based on Mr. Courtney's post):

Some people think this issue matters. Others don't. My experiences tell me it matters. Can I prove it? Not without tests. Can you prove it does not matter? Not without tests.

If a transsonic is fired a hair above speed of sound from muzzle then it's buffeted by sound barrier turbulence continuously from the time it leaves the barrel. It must cross the sound barrier twice and spend time at the sound barrier. I think that matters and my miserable experiences with transsonic rounds say it matters.

i.e. - at leaving the barrel the bullet breaks just above the sound barrier, but not far enough to get ahead of turbulence. Then as it slows it must cross the sound barrier a second time. Then slightly subsonic it gets buffeted all the way to the target because it's still close to SofS. I think 1100 to 1130 fps should be the worst possible muzzle velocity for accuracy. My .40 cal used to have about 1125 fps muzzle velocity and it was NOT accurate.

Challenge Follows:

I think a hand loader with a 9mm, .38 Spl, or .40 cal could easily experient with different velocities from 1080 to 1175 fps until they found the velocity that gives the worst accuracy at 25 yards. I'm almost certain the worst muzzle velocity is between 1080 and 1130 fps. Probably between 1100 and 1130 fps.

Would someone like to try this? It would be easier to find the least accurate velocity than to find the most accurate. Finding the least accurate muzzle velocity and comparing its accuracy to 1050, 1225, and 1250 fps accuracy would prove or disprove the whole premise.

Perhaps the best and most efficient approach would be to use the Speed of Sound calculator (url provided by Dawg) to calculate the speed of sound in your area based on your local temp and other conditions.

http://www.sengpielaudio.com/calculator-airpressure.htm

Then load some ammo to shoot muzzle velocity at your local SofS. Then load some to shoot 10 fps above SofS, some 20 fps above, some 30 fps above, and some 40 fps above. Then see how accurate each is at 25 yards. That really doesn't sound too difficult or labor intensive to me. (Easy for me to say. Ha, ha.)

Sectional density also matters. Therefore, for the tests at 1050 fps you should use heaviest bullet that will go 1050 fps muzzle with standard pressure. Likewise for each of other tests. Use the heaviest bullet that will give the velocity you intend with standard pressure.

Use the same gun for all tests.

Would anyone like to take up the challenge? You'd need to be a reloader with a chronograph and the ability to calculate the Speed of Sound for your local conditions. I'd suggest loading ammo based on a speed of sound based on an air temp that is a common temp in your local area. Then do the accuracy (shooting) tests when the air temp is right. Don't worry about humidity because I don't think that matters a lot.

You could invent you own testing system as long as you keep records of what you do and why. I'm just trying to give ideas about how to go about testing.

If anyone would like to take up the testing challenge, we can find out how much this topic matters at 25 yards. If no one will take up the challenge, then I have nothing further to say because we've already talked this to death. What we need now are some tests.

The above paragraphs are my challenge to the reloaders out there. This should not be difficult to test because I've given you a narrow range of velocities to test at 25 yards. You'd need a chronograph and a 9mm, .38 Spl, or .40 cal. Other guns could work to, but I think those would be best. A 9mm would be the ideal test gun, but a .38 Spl would be good too. You'd need to be able to calc speed of sound and sectional density of the bullet. You'd need to keep careful written records.

Theoretical discussion has taken us as far as it can. What we need now are tests. If you want to test and live in Pacific Northwest, I'll share my Shooting Chrony with you.

I've thrown down the guantlet. Any takers?

Thanks from wbond

P.S. - this would be a great one to send in to Myth Busters, but I have no doubt they'd screw it up. They're gun knowledge is pitiful and their attitude seems to lean toward the anti-gun hollywood liberal, in my opinion. I have more confidence in HighRoad guys than Myth Busters. We could prove or bust this once and for all among ourselves.

 

[T.Stahl]

FYI - many sources (including textbooks) say elevation is important to SofS. Many other sources (including textbooks) say it is NOT important. Many other sources say elevation indirectly affects SofS.

I'm voting for the indirect theory because that would mean we are both correct, or partly correct. The sources I originally looked at said elevation matters. Perhaps it doesn't. Not sure.

I'm now willing to concede that maybe it does not matter, or only matters a little, or only indirectly matters.

Elevation does NOT matter to our overall accuracy discussion because the main topic is whether SofS affects pistol accuracy at 25 yards or not.

Below are a list of sources about speed of sound and what matters. Temp matters the most. That's one thing all SofS sources agree on. That's one thing you and I agree on.

Here's a partial list of my sources (notice that they do not agree about elevation):

Speed of Sound Sources
http://www.answers.com/topic/speed-of-sound
See the Wikpedia section a little ways down the page.

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

Once more: The reason many sources imply a dependence of the s.o.s. on the elevation=pressure is that they give (misleading!) examples similar to the one in your Wikipedia link:

Altitude Temperature m/s km/h mph knots
Sea level 15 °C (59 °F) 340 1225 761 661
11,000 m–20,000 m
(Cruising altitude of commercial jets,
and first supersonic flight) -57 °C (-70 °F) 295 1062 660 573
29,000 m (Flight of X-43A) -48 °C (-53 °F) 301 1083 673 585

In those examples they give the s.o.s. for usually two conditions:
- the international standard atmosphere at sea level, which happens to assume an air temperature of 288.15K (15°C)
- the international standard atmosphere above 11,000m (~35,000ft), where the air temperature has dropped to 216.65K and then remains constant until it increases again at even higher altitudes. (see table in Wikipedia link!)

Nevertheless, read the link you provided. There is no p in c=sqrt(kappa*R*T) and neither kappa nor R nor T depend on p.

Many other sources say elevation indirectly affects SofS.

Only because the temperature usually drops with increasing altitude.
But then you could also say that the s.o.s. is affected by latitude or the higher the closer you get to the equator, as it's usully much colder far north and far south.

 

[Sylvan-Forge]

VofS

wbond,

I'm with you, VofSound does matter.
I postulate the affects are substantial even to 10yards.
I currently have some fairly decent reloading tools, although before I begin submitting test results I would like to acquire a ransom rest, high-end reloading dies,
and calibrated weather metering device. A pyrometer would be nice to have as well, but may wait for later.
This test will be run concurrent with powder-type temperature-effect testing.

It may take me several months to get these goodies, but once I get going on testing I'd be glad to share them with
you, wbond, and with the THR community.

Perhaps someone else can supply test data more immediately?


Best,
oo7

 

[unspellable]

Standard velocity vs high velocity 22LR

The standard velocity 22LR is just subsonic in a rifle while the high velocity is transsonic. However, from a pistol, both rounds are subsonic. The standard velocity round may still be more accurate because its reason for being is accuracy and it's probably put together with better tolerances than at least a cheap high velocity round.

This leads to another question. I have a box of Remington 22LR prominently labeled as subsonic with a heavier than standard bullet. Supposedly for low noise. Is there a substantial reduction in noise going from just subsonic to substantially subsonic?

 

[Jim Watson]

I think the "wbond challenge" pretty well spells out what needs to be done to go from theorizing to results. But what is keeping you from doing the work? Why me? A .32 H&R is capable of covering the velocity range of interest without much kick. I'd have to get Ransom Rest inserts for a particularly accurate pistol and do a lot of baseline chronograping to establish loads at, say, 25 fps increments to even get set up for the sub- trans- supersonic comparison.
Maybe oo7 will handle it.

 

[Michael Courtney]

I think the "wbond challenge" pretty well spells out what needs to be done to go from theorizing to results. But what is keeping you from doing the work? Why me? A .32 H&R is capable of covering the velocity range of interest without much kick. I'd have to get Ransom Rest inserts for a particularly accurate pistol and do a lot of baseline chronograping to establish loads at, say, 25 fps increments to even get set up for the sub- trans- supersonic comparison.
Maybe oo7 will handle it.

Lots of factors affect accuracy and will tend to confound the effects of the sonic transition unless you've got a set-up that consistently produces 1" groups at 25 yards from all other contributions to inaccuracy other than the sonic transition. A lot of handguns, bullets, etc. won't meet this requirement even from a ransom rest. If you want to be sure to isolate the sonic transition from other factors that impact accuracy, I'd say your best bet is to use a Contender or Encore or shoot the pistol bullets from a scoped in-line muzzleloader. A very accurate revolver will also work, but there are a lot of revolvers that are not accurate enough for the experiment.

And by "accurate" one needs a gun that meets a minimal accuracy standard with EVERY LOAD (at least at ranges that do not include a sonic transition) not just a gun that is a sweet shooter with carefully selected loads. In some sense, this is why studying the sonic transition might be better achieved by studying the accuracy of supersonic loads at different ranges and observing that the accuracy suddenly takes a nosedive about 25 yards beyond the transition range.

In any case, one needs a careful experiment capable of distinguishing the sonic transition effects from every other potential effect on handgun bullet accuracy.

Michael Courtney

 

[Jim Watson]

I'd take some showing that data from saboted bullets in a muzzleloader would transfer well to a pistol. A Contender would work better, if you did not have a Ransom Rest for a real pistol.

 

[wbond]

To Stahl and Dawg re elevation and humidity

The speed of sound calculator at the link submitted by Dawg shows that temp is the main factor affecting S of S, which supports Stahl.

It also shows that elevation and humidity matter a little bit each, but not enough to worrying about. This supports Stahl more than me, but also splits the difference.

In conclusion, thanks to Stahl and Dawg, I now know elevation and humidity affect the speed of sound a little bit, but not enough to matter. i.e. - they are not signifigant factors. Temperature is the signifigant factor.

Stahl was right about elevation not mattering. I was right that it does affect S of S, but since its effect is insignifigant, for all practical purposes elevation doesn't matter.

 

[wbond]

To Jim Watson: It doesn't have to be you...

I think the "wbond challenge" pretty well spells out what needs to be done to go from theorizing to results. But what is keeping you from doing the work? Why me? A .32 H&R is capable of covering the velocity range of interest without much kick. I'd have to get Ransom Rest inserts for a particularly accurate pistol and do a lot of baseline chronograping to establish loads at, say, 25 fps increments to even get set up for the sub- trans- supersonic comparison.
Maybe oo7 will handle it.

It doesn't have to be you Jim. Did I say it had to be you? It could be anyone or a combination of people. Your post was only one of many challenging my theory that Sound Barrier vs Accuracy applies to handguns. The theory part being that it matters to handguns. No one disputes it matters for rifles at rifle distances.

There are many posts that disagree with me. Many that agree with me. Many that find it interesting but don't have an opinion.

I just think its time to do some tests. Your post was fine and I have no problem with you at all. The challenge is to everyone. I've heard the objections so many times, but no proof. Likewise I can't give any proof either.

None of us can offer proof at this time, which is why we need to test.

Why don't I do the testing? I can give you several good reasons for that:

1) I don't have time to learn to reload and don't have the interest.

2) I sold my house and now live in a one bed apt and don't have room to reload.

3) I already believe my theory is true. Furthermore, if I'm right, then following my velocity guidelines would be helpful. If I'm wrong, then following my velocity guidlines won't hurt anything. Either way I'm personally satisfied that I'm right and I can choose appropriate factory loads that suite my purposes just fine for anything I shoot.

4) It's true that the .32 Mag can be sub, trans, or super sonic from a 6" barrel. However, I have a 3" barrel. I could only do sub and trans. I'd never get adequately super sonic from a 3" barrel. Same with my 9x18.

5) I can't use a .38 Spl or 9mm to do the testing because I don't own them and my hands likely can't handle hotter loads in these. In fact, my hands might not even handle normal loads. My left hand is held together with 4 screws and my right hand has a party fused thumb and a totally fused wrist. I'm not willing to cripple myself further for a test.

OK. I could use a Ransom rest, but where am I going to get one and how much do they cost?

6) Since I'm held down to a .32M with 3" barrel or a 9x18 CZ-83, I basically have few velocity choices for my guns: 1070 fps or less with a 95 gr 9x18 bullet, or about 1100 fps or less from my .32 Mag. However, with the .32M I feel a lot of hand pain with hotter loads. I'm happy with 1050 fps from my 32M and my 9x18 for both recoil reasons and accuracy.

7) Even if we prove that a 9mm Para, .38 Spl, .40 cal, etc are better with various loads, I personally probably won't be able to benefit from that knowledge because my hands probably can't take it. For me personally, I'm going to be around 1050 fps from my .32M and my 9x18. The only difference ballistically between them is the bullet weights. .32M is 85 gr. 9x18 is 95 gr.

This whole discussion is academic for me because I'm not likely to shoot supersonic 9mm or .38 Spl and will certainly not be shooting a .40 cal.

However, there are many other people with 9mm, .38 Spl, .40 cal, .38 Super and others who might benefit substantially from the tests.

Jim, please don't be offended at the challenge. I meant to challenge everyone. I personally am interested, but not motivated to test myself, unless I used a .22 rifle shooting store bought .22 LR ammo to do it.

 

[wbond]

Test proposal

Actually, an alternative test proposal.

I could personally use a .22 rifle with .22 LR store bought ammo to compare subsonics to transsonics on 25 yard targets. I did this same test years ago at 50 yards and was satisfied Velocity affected Accuracy. It mattered at 50 yards. I've never tried this test at 25 yards, but could. Would this be a satisfactory test at 25 yards? I'd be willing to do that.

I could use many different brands of subsonic, transsonic, and super sonics. Actually, I'm not sure if the .22 LR can give a decent super sonic speed. However, my .22 Mag rifle can. However, that would bring a second rifle into the test. One thing a .22 Mag rifle could test very well is if faster super sonics are more accurate than slower super sonics.

It is rifle fact that with subsonics, the slower they go the more accurate they are down to 700 fps, which is the sweetest accuracy according to Olympic target pellet rifles. With super sonics, the faster they go the more accurate. The other part of rifle fact is that transsonics are NOT accurate. My theory is that this also applies to handguns at 25 yards.

My fear about using a .22 LR for testing is that people would say the .22 LR has less sectional density and is therefore more affected by sound barrier turbulence than a larger, heavier bullet (like a .38 or 9mm). Anyone saying this would be correct. Therefore, I'm concerned that a .22 LR test might NOT resolve things.

I do have a sighting in rest for a rifle and a chronograph. Would you guys accept a test done with a .22 rifle shooting store bought .22 LR ammo? Or would you say it doesn't count because the bullets aren't pistol bullets? i.e. - would you accept this test or would you cry foul?

To be frank, I'm not sure if this would be a relevant test because the bullets are much lighter. What do you guys think?

 

[Jim Watson]

I don't know if it would be conclusive, but it would be relevant, if done right.

Select an accurate brand and lot of HV ammo on the basis of short range groups so as to get a handle on supersonic performance, then shoot at long enough range for it to drop sub Mach; versus target ammo.

As a sidelight, there is an offshoot of BPCR silhouette shooting with .22 subcaliber adapters in .45-70s and an increasing number of .22 single shots. Range is up to 200 yards; developers found that a .22 at 200 yards was about as subject to the wind as a .45-70 at 500 metres. Competitors report that they get better results with a good .22 HV at that range, that the subsonic match ammo so accurate at 100 and less just kind of loses its way at double the distance.

 

[wbond]

To Unspellable:

With regard to the accuracy of subsonic .22 LR rounds. The slower subsonic is likely to be more accurate for several reasons:

1) It's probably a heavier bullet with more sectional density. This matters a lot with a little bullet like a .22 LR.

2) Slower subsonics are inherantly more accurate than faster subsonics. According to pellet gun makers, 1050 fps is about the fastest subsonic that gives acceptable accuracy. As you decrease velocity below 1050, the accuracy will increase. The most accurate velocity is 700 fps.

3) Perhaps the slower, heavier target rounds are built to higher tolerances like you said.

It's probably a combination of all 3 things above.

As for which makes the most noise, I don't know that I can answer that for a .22 LR. However, I can tell you that with pellet guns, the faster they go, the most noise they make. This is true with the subsonic pellet guns. The supersonics are really noisy. I don't know how much noise is from the gun and how much from the pellet.

The standard velocity 22LR is just subsonic in a rifle while the high velocity is transsonic. However, from a pistol, both rounds are subsonic. The standard velocity round may still be more accurate because its reason for being is accuracy and it's probably put together with better tolerances than at least a cheap high velocity round.

This leads to another question. I have a box of Remington 22LR prominently labeled as subsonic with a heavier than standard bullet. Supposedly for low noise. Is there a substantial reduction in noise going from just subsonic to substantially subsonic?

 

[Michael Courtney]

I'd take some showing that data from saboted bullets in a muzzleloader would transfer well to a pistol.

No it wouldn't. Once a pistol bullet is in flight, it only knows its direction, velocity, and rate of spin. It has no "memory" whether it was fired from a pistol or a muzzleloader.

Observing groups open up from 2-3 MOA to 6-12 MOA within 25 yards of crossing the sonic threshold (as velocity is lost to wind resistance) is conclusive evidence that the sonic transition has a negative impact on accuracy, regardless of what was used to launch the bullet in the first place. I mention the muzzleloader because it is much more widely available than the Contender/Encore (especially in pistol calibers) and because the velocity of saboted pistol bullets in the 1100-1500 FPS range are very easy to adjust to the desired quantity in a muzzleloader.

Of course, there is nothing wrong with using a Contender or Encore in the appropriate caliber. However, a single .50 Cal muzzleloader can be used to study any .40, .429/.430, or .451/.452 pistol bullet at any relevant velocity, and an inline .45 can be sued to study any .355, .357, or .40 pistol bullet at any relevant velocity. Doing the experiment with conventional cartridge loads will require a number of trips from the range to the reloading bench. The muzzleloader allows for load tweaking in real time to dial right in to the desired velocity with a single trip to the range.

Michael Courtney

 

[wbond]

To Jim: 25 yards

I don't mean to be argumentative, but the point of the test is whether sound barrier matters at 25 yards with pistol bullets at pistol velocities. The test has to be done at 25 yards, in my opinion. If I were using a .22 LR, I'd have already deviated from the "pistol bullets" part of the test. If I tested at a longer range, then the test would be even farther from it's intent.

The ideal test would be with handguns and handgun bullets at 25 yards. Even going to .22 LR is a corruption of the test, but I could live with that if others could. However, I think we do need to stick to 25 yards.

===================================

With regard to wind drift and rifles at long distance. The more super sonic bullets give wind less time to push on them. However, wind drift is NOT relevant to handguns at 25 yards.

I don't know if it would be conclusive, but it would be relevant, if done right.

Select an accurate brand and lot of HV ammo on the basis of short range groups so as to get a handle on supersonic performance, then shoot at long enough range for it to drop sub Mach; versus target ammo.

As a sidelight, there is an offshoot of BPCR silhouette shooting with .22 subcaliber adapters in .45-70s and an increasing number of .22 single shots. Range is up to 200 yards; developers found that a .22 at 200 yards was about as subject to the wind as a .45-70 at 500 metres. Competitors report that they get better results with a good .22 HV at that range, that the subsonic match ammo so accurate at 100 and less just kind of loses its way at double the distance.

 

[Jim Watson]

I understand that the point of the discussion is handgun performance at handgun ranges; I just brought up long range shooting to show that other factors can outweight the transition under extreme conditions.

.22 lr has a very low BC and I would think it usable for preliminary work, if you could find some HV that was accurate in the test gun.

 

[Michael Courtney]

I don't mean to be argumentative, but the point of the test is whether sound barrier matters at 25 yards with pistol bullets at pistol velocities.

You're skipping straight to the intended application of the knowledge, but doing so makes separating out the confounding factors much harder. From a scientific standpoint, it is always better to begin by isolating the effect under study from as many confounding factors as possible, and then once the effect is understood in isolation, creating a more complex experiment to apply more directly to the intended application.

The effect really under discussion is whether or not the sonic transition has a negative impact on accuracy, and (if so), how large is the effect? The application of whether this results in a negative impact on pistol velocity inside of 25 yards is a specific application of a more general problem. However, jumping straight to the application introduces confounding factors so that (in the absence of prior results from longer range experiments) it is more difficult to interpret the results of the experiments at 25 yards.

The test has to be done at 25 yards, in my opinion. If I were using a .22 LR, I'd have already deviated from the "pistol bullets" part of the test. If I tested at a longer range, then the test would be even farther from it's intent.

If you limit the test to pistol bullets at 25 yards, you may well conclude that subsonic is more accurate than supersonic or trans-sonic, but you will just be guessing as to the causal reason. It is very difficult to conclude that the transition from supersonic to subsonic is the cause for the loss of accuracy without quantifying the accuracy at a close range (before the sonic transition), and comparing this with the accuracy at a longer range (some distance beyond the sonic transition).

25 yards does not provide eough range variation to work with, and also restricts the range of initial velocities to under 1125 FPS or so to even have any sonic transition. Even with a muzzle velocity of 1125 FPS, a BC of 0.15, and a speed of sound of 1080 FPS, the sonic transition does not occur until past 20 yards, so there is not much room left for the bullet to deviate from the path after the sonic transition. Very few pistol loads are "just barely supersonic" in the required manner to see the transition early enough in the trajectory to effect 25 yard accuracy.

Michael Courtney

 

[Jim Watson]

Agreed, precison pistol shooting is normally done at 50 yards/metres. (NRA slowfire, PPC Match 5, ISU freepistol.) (Unless you are a silhouette shooter and the requirements are WAY different for that.)

 

[wbond]

What speed?

I was watching the history channel last night and they talked about transsonic flight and how during WWII faster prop fighters and also subsonic jet fighters were going transsonic during dives and getting vicious turbulence. The turbulence was so bad they would sometimes lose control and crash.

The Germans figured out that a swept wing design was more aerodynamic and would slip stream the air better. They also figured out that being more aerodynamic (i.e. - less drag) delayed the effects of transsonic turbulence until a higher speed and when it did occur, it was less violent. That was the original reason for swept wings.

To apply that to bullets, pointed bullets would be least affected, round nose second least. Hollow points would be more affected. Therefore, the test should done with hollow points since that's what people use for SD.

Also, the use of HP would be more applicable to self defense too.

 

[wbond]

Possible test

I intended to do the .22 LR tests at 15 yards and 25 yards using a rifle for sub and trans. Then repeat with a .22 Mag rifle for supersonic. I suppose it could also be done at 50 yards, but I can already say with certainly that it matters at 50 yards, but no one shoots self defense at 50 yards.

When I was young, I did thousands of rounds of target practice with a .22 LR rifle at 50 yards. I know for a fact the sound barrier matters to accuracy at 50 yards, though I can't prove it to you at this time.

My concern with spending my time running any tests is time and money. I wouldn't have time until later spring or summer.

I'm concerned that no matter what type of tests I might do, a substantial portion of people would not accept the results, which would make the whole thing a waste of time and money.

Therefore, I'm NOT going to test anything unless we can agree on a test plan that I can afford both the time and money for.

If this whole thing does NOT get tested, it's not a big deal to me. However, if I'm going to put forth effort, time, and money, then it will affect my life. So I don't want to waste my time and money.

Anyone else is welcome to test this themselves. The more testers the merrier. It would certainly be interesting if some people tested with .22 LR rifle and .22 Mag rifle while others used handguns (ideally .38 Spl or 9mm) and maybe the muzzle loader tests proposed.

I'll wait a week or so to let people weigh in on this. Then I'll come back to this thread to see if we can form a concensus for a test that I can afford the time and money for.

Thanks