Velocity vs. Accuracy - Sound Barrier

[wbond]

One last thought for the week

As I said in prior post, I'm going to stay away from this discussion for 1 week to let the rest of you hash out a test plan that we can all accept and that I can afford to do, if that's possible.

Anyone else, please do whatever tests you want.

I suspect that no concensus will be reached on acceptable tests that I can possibly afford the time or money for. I hope a concensus can be reached, but I doubt it.

That said, I'm going to close my comments for now with the following:

Until someone tests the premise, I'm going to stick with my theory that velocity affects accuracy at handgun velocities and distances (15, 25, and 50 yds).

All target handguns and ammo that I know of are subsonics. That must be for a good reason. I'm defining a handgun as anything with a 6" barrel or less. Once you get beyond 6" it's not carryable. In fact, once you get beyond 4" it's not practical to carry.

Thompson Center Fire "handguns" are hand held rifles shooting rifle ammo, so they don't count.

Any true handguns that are target guns are subsonic shooting subsonic ammo. At least as far as I'm aware of. The preference for subsonic target handguns and target ammo for use at 50 yds, 25 yds, and 15 yds for target shooting strongly suggests I'm correct in my accuracy theory (at handgun distances).

Has anyone ever heard of transsonic target ammo for a target handgun? No. There aren't any made as far as I know. That's for a good reason I'm sure.

Also, there are few, if any, supersonic target handguns and ammo for a good reason.

I rest my case on that until this matter is tested.

Also, I'd like to remind everyone about the handgun ammo manufacturer who told me it doesn't matter: He specifically said, "It doesn't matter at 10 yards and closer, which are the self defense distances". Those were his exact words as close as memory serves. His words imply it might matter beyond 10 yards. Read between the lines.

Lastly, my personal experiences at 50 yards and 25 yards with .22 LR and handguns tell me it matters.

That's all I have to say on the subject until we can agree on tests, if we can agree.

I'm staying away for one week so anyone interested can discuss possible test procedures.

Thanks

 

[k_dawg]

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.

?

There are a few 22lr rounds that are transsonic/barely super sonic out of a pistol. I know the CCI Velocitor and 32gr stinger are. They are horrible [ accuracy wise ] in my MarvelI and Kimber .22 conversion kits at 10-50yards !!!

But great in my 22lr rifles to 50yards.

 

[Michael Courtney]

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.

This is a poor experimental design because you have no way to know whether the accuracy differences are coming from the sonic transition or some other factor. Each gun and load is a law unto itself with regards to accuracy and the experiment you describe cannot ascribe any causal reason to any accuracy differences you observe.

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.

An experiment is not good or bad because people accept the results, but rather because it isolates and carefully quantifies the effect under study in such a way that the work can be repeated and extended by others.

It's not enough to test the accuracy of subsonic, supersonic, and transonic loads. Accuracy needs to be tested in such a way that all other contributions to inaccuracy are very small. In most handgun shooting, the greatest accuracy limitations are the shooter himself (thus the suggestion to use a ransom rest) and the mechanical limitations of the handgun itself. Since the desire here is to study the effect on accuracy of the sonic transition, one needs to remove both the common mechanical limitations of most handguns, as well as the shooter error from the situation as much as possible. Using a Contender, Encore, or scoped in-line muzzleloader accomplishes this goal. Most ordinary defensive handguns are simply not accurate enough to remove the fundamental mechanical limitations, thus your study would be open to the criticism that some other effect (other than the sonic transition) was responsible for any observed accuracy differences.

Michael Courtney

 

[Jim Watson]

Not ALL target handgun loads are subsonic. There is some very good shooting being done in NRA Service Pistol with the Beretta and 9mm at supersonic muzzle velocity. I don't know the 25 and 50 yd velocity though, it might be hot enough to remain supersonic at the target.

 

[Michael Courtney]

Until someone tests the premise, I'm going to stick with my theory that velocity affects accuracy at handgun velocities and distances (15, 25, and 50 yds).

Of course, just about any handgun will have a favorite velocity with a particular bullet. The more important issus is why. Unless one can elucidate general principles that apply to all handguns, then one doesn't have any predictive sort of science, one ject has the anecdotal knowledge that he should fool around with different velocities until he finds one that is a good match to a particular gun.

All target handguns and ammo that I know of are subsonics. That must be for a good reason.

Perhaps the "crack" of supersonic bullets is disconcerting to shooters and introduces more human error?

Thompson Center Fire "handguns" are hand held rifles shooting rifle ammo, so they don't count.

Just about all the common pistol calibers are available also.

Any true handguns that are target guns are subsonic shooting subsonic ammo. At least as far as I'm aware of.

Has anyone ever heard of transsonic target ammo for a target handgun? No. There aren't any made as far as I know. That's for a good reason I'm sure.

I've got a Sig Trailside target model that shoots transonic ammo pretty well. Better than the subsonic match ammo I tried in it. But then, maybe I'm just more immune than most shooters to flinching in anticipation of the super sonic crack.

You really need an experimental design that eliminates confounding factors.

Michael Courtney

 

[Sylvan-Forge]

Transonic Flight...

...well documented it seems, but since my moniter is shot (literally), I'm stuck using the TV set instead, making research a pain in the arse.

On one of the .edu sites I could see well enough to read,
was about the history of supersonic flight and its study.
Some early experiments had shown shock wave disturbances at transonic speeds (0.8-1.2 VofS) on miniture airfoils measuring maybe a couple inches across and likely a quarter inch at wing root ever smaller toward the tip, with thinner, swept airfoils encountering shock (compressibility burble or some such) waves in the 0.9-1.1 range.
http://history.nasa.gov/SP-4219/Chapter3.html

I'm thinking blunts and spires here, along with their corresponding BC's.

On one of Sierra's websites, they speak of the transonic fluctuations in BC :

4.5 Ballistic Coefficient Variations with Muzzle Velocity near the Speed of Sound

There is one velocity region within which the ballistic coefficient of every bullet we have tested exhibits dramatic, radical changes. This velocity region is from about 900 to around 1200 fps, which includes the speed of sound (approximately 1129 fps in Sierra’s test range). The purpose of this section is to describe then bullets by simply loading and firing many rounds for each bullet type within the 900 to 1300 fps velocity range. ..
http://www.exteriorballistics.com/ebexplained/4th/45.cfm

I didn't root around since I can't see the darn menu buttons.

The trouble with using long barrels is due to barrel harmonics (vibration), which IMO would confound the experiment. A pistol length barrel would be best. A good quality automatic may suffice, naturally a securely mounted bench-rest type pistol with a bolt action would be better. Maybe a TC contender with the shortest possible barrel.

Without getting into extremely expensive equipment, like IR camera arrays, complex acoustical mapping gear, radar tracking, etc.. I think a decent experiment could be put together.

Using concise handloads, a mechanically secured pistol,
a chronograph or two, some simple paper targets,
a controlled environment (indoor range), a seperate room thermometer (in conjunction with thermostat maybe), and very careful record keeping.

Example Test (Using identical cartridge components-Only variable is amount of powder used) :

Indoor Range Temp : 70 deg F (21.111 deg C)
Wind Speed : 0
Humidity : 50%
VofS Calculation : 1130.873 ft/s (344.69 m/s)
Transonic Range (0.8-1.2) Calculation : 904.7-1357 ft/s

Subsonic Testing : Target Speed 850 ft/s. Should not to exceed 880 ft/s

Fire 10 rounds to adjust POI and to warm barrel, clean.

Set-up chronograph(s) If using 2, place second at 3/4 to target.

Fire 10 groups of 10 rounds, recording speed of each round fired, cleaning between each group and replacing target for each group.

Record group sizes for ten targets.

The next phases of the experiment would be for the transonic range which might be broken down into several
sub-tests, Target velocity ranges at 0.8, 0.9, 1.0, 1.1, and 1.2 should probably be studied by the individual shots. Perhaps groups that are marked by shot # individually on the target so that they can be correlated with their chronographed velocities. Multi-shot groups as peformed in the subsonic portion should likely be performed for the transonic tests.

Following up with supersonic testing (like the subsonic) in the range of 1.2-1.3 to round off the experiment.

All the test targets groups averaged.
I think the proof will be found on those groups that are individually tracked by the shot, likely showing radical flyers for those rounds that hit the not-so-sweet spot, as well as groups that just won't group around that corresponding not-so-sweet range.

It would enhance the data set to have multiple tests done on multiple bullet styles. Maybe diff powders too.

It would be more difficult to observe the super-to-transonic transition seeing that even very low SD commercial bullets will not drop from 1.2-1.3 into transonic ranges on typical 25 yard indoor ranges,
unless you can get ahold of some really light projectile, maybe.

Ok, need food and drink now, me mind is tired..

Oh, by the way hello all, I'm new here .. this thread got me to become a member

 

[wbond]

To 007:

Great post.

I'm going to read up on your info and links.

With regard to myself doing a test, it appears to be beyond my budget and ability to do so in a manner that would be accepted by others.

I have no need to prove it to myself. Actually, I have no need to prove it to others either.

However, if I can enlist the support of the people at my local pistol range, maybe the group has the resources to do the test, if they have the interest.

The principles are well proven with rifles. What is not proven is how much they matter at handgun distances.

I'm moving on to other subjects in other threads now.

However, I do appreciate your post. It was excellent and I recommend everyone check out the info at Speer that you posted. Thanks.

I also appreciate everyone else posts and participation (whether we agree or not). Thanks.