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  #1  
Old 02-25-2017, 10:53 AM
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Ammo going Trans-Sonic



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I haven't read all of the threads in this "long range rimfire" forum, but I was wondering if anybody has ever tried this experiment:

Test a rifle that is known to be accurate with high velocity .22 ammo (36 to 40 grain bullets at about 1200 or 1300 fps from muzzle) at various distances from 50 yards to 200 or 300 yards, noting both group size and muzzle velocity (over a real chronograph) at all distances, at least as far as you can shoot through the screens of your chronograph reliably.

WHAT I WANT TO KNOW IS: how much is accuracy degraded due to crossing from supersonic flight to subsonic flight. This should happen at around 50 to 80 yards, depending on the gun and ammo combination.

By 150 yards the bullet will certainly have had some distance of supersonic flight,

and at 200 yards more than half its time in the air would have been spent after having transitioned below Mach 1.0 and experienced whatever turbulence or stress factors come with that.

I REALIZE that most long-range .22LR shooters choose match ammo that fires at subsonic speeds even as it leaves the muzzle. Great. I've got that ammo, too.
But I'm asking "what if" I were to use the HV stuff. How much would that cost me, in a rifle that happens to shoot it well, and for which there is not any measurable difference in accuracy between standard velocity ammo and high velocity ammo of the same quality class at distances of 25 to 50 yards?

Has anybody tested this?

Or seen any tests done by others?
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  #2  
Old 02-25-2017, 12:30 PM
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Effects of .22 non magnum lead heeled ammo going sub sonic

I had the occasion to spend three weeks at the Fulton Armory years ago. Company I ran made capital equipment for them. I mention that because of what follows:

The Armory did extensive research about the transition/nutation/yaw encountered when a .22 non magnum lead heeled bullet breaks the sound barrier (High Velocity) as compared to those that did not (Standard Velocity)

The testing was done in a tunnel at 100 yards with all the modern equipment of that day. Same rifle, same benchrest set up, same shooter. Special run of ammo where the cases were the same, priming compound the same, bullets the same, loaded on same equipment, weight of powder the same but different burn rate, same chamber pressure etc. If memory serves they shot 2,000 rounds of each loading.

The results were that the deflection that could be directly attributed to the sound barrier interference was .08" at 100 yards and the re-stabilization of the bullet was measured as less then a nano second and was not anywhere near what folks said it would be. High speed photography proved that.

Many folks will "speak from experience" that the adverse effects caused by that transition are large, like 1" or 1.5" but there are a whole bunch of other factors that can easily cause that variance.

noremf(George)

Last edited by noremf; 02-26-2017 at 09:35 AM.
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  #3  
Old 02-25-2017, 10:01 PM
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The transition occurs at about 43 yards.

You can see the difference even at 50 yards with no wind. It's as if the bullet is Knuckleballing. You can observe the behavior through a scope.

You get about 1.5 times the wind with HV.

Its even more pronounced with a 9mm running at 1200 fps. That's why you never see anybody publish a ransom rest result for a 9mm pistol at 50 yards. It's just not a valid accuracy test.

HV at 200 is still worthwhile practice. It just depends on what you're doing.

I primarily shoot offhand at 200 on the NRA high power targets. HV is fine for that. I'll shoot almost the same scores I would with an AR just with a lower x count.

If you're shooting benchrest or prone probably not so much.

The issue really should be put to bed. Denying the effect of the transition is like advocating the flat earth theory.

You can easily observe the effect through a 20x scope at 50 yards.

It's all relative. 3 or 3 1/2 MOA versus 2 MOA for standard velocity.

Last edited by landshark; 02-25-2017 at 10:04 PM.
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Old 02-26-2017, 05:30 AM
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All I see are very smooth ellipses. No sudden changes as with a knuckleball.
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Old 02-26-2017, 08:05 AM
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I can't see a thing crept new holes in the paper.
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Old 02-26-2017, 09:11 AM
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Seeing a bullet in flight

While you can often see the distortion of the air which is caused by the shock wave if the conditions are good to excellent, that does not reflect the stability or non-stability of the bullet itself. Simply the movement of air around it and you are seeing it from the back. Would be like looking down in a whirlpool.

You can see the rings but you cannot see anything in the center.

Often called a bullet trace.

When viewed from the side with a high speed camera at 1200X it looks like this as it travels down range.



Looking at the shock wave at the base of the bullet it is pretty focused whereas as it gets farther away it becomes distorted.

If you focus a spotting scope approximately 10 yards in front of the target, you can see the base of the bullet as it goes through that focal plane with decent lighting.

Doing that is a requirement for silhouette spotters as they can "call the shot" before the target is knocked over.

Even doing that the stability of the bullet will not be visible from the back because it is "clouded" by the distortion of the air from the shock wave.

I shot silhouette 50 weeks out of the year on the average for 25 years to the day and spotted for my spotter when not shooting myself and neither I nor any other spotters could see a bullet wobble. Shock wave variances sure which if it was windy could tell you why a bullet was pulling away from them. The base of the bullet going through the focal plane if the spotting scope, and the ones used often are 60X-80X and I used a Celestron Edge HD Optical Tube Assembly with eyepiece inserts from 40X to 240X?

You bet and that is what spotters are there for.

I am not a ballistician and don't claim to be, but I had to spend a lot of time with them at Government armories and firearms manufacturers as the company I ran provided capital equipment for them.

If memory serves objects visible for .003 seconds become blurry to the human eye and faster than that are invisible. The transitional time for the recovery from yaw is measured in nano seconds which are .0000001 seconds.(A billionth)

I don't know anybody that denies that yaw is not introduced when the sound barrier is broached but know lots of folks that look at that kind of stuff for a living that point out that shock waves are rarely if ever the dominant factor in that yaw.

Can you have an adverse effect on the cone of fire cause a deflection of 1" at 100 yards between subsonic and supersonic loads? Sure. Is breaking the sound barrier the dominant cause? Small chances of that. Are the center of pressure and/or center of gravity or how good the longitudinal axis is between the bullets the causes? Most often. Will they match the rifling? Sometimes.. Will they match the muzzle velocity (MV)? Sometimes. Will they be out of whack because the bullet is either longer or the driving bands slightly thicker or more of them? Yup.

Can you have an adverse effect on the cone of fire cause a deflection of 1" at 100 yards for subsonic rounds? Sure but not because they are breaking the sound barrier as they don't.

noremf(George)

Last edited by noremf; 02-26-2017 at 09:36 AM.
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  #7  
Old 02-26-2017, 09:26 AM
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I did a science project about this very thing. While my controls were were not nearly as controllable as they might be in a lab, I shot 4 varieties of CCI ammo of varying velocities out to 100 yards at 25 yard increments. The two loads that went transonic gave mixed results. Accuracy was measured in MOA, shot with the the same rifle on the same day, under the same conditions. One of the loads showed a 30% decline in accuracy, the other remained the same. These were the results that I got with my science experiment. Your results may vary.
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  #8  
Old 02-26-2017, 12:42 PM
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Sorry to clarify. What I meant to say is if you call your shots through a scope you can see where the shot broke and where it landed.

By knuckleballing I mean to say it's less likely to be on call.

One way of measuring the quality of ammunition is a certain percentage will fall within a given diameter, another percentage within a larger diameter, etc. I think that's how the Russians grade military ammunition.

I used to shoot the RayVin reduced 600 target a lot at 50 yards

With Wolf MT at 50 yards In a 10 shot string I expect half the shots to be pretty much on call, the other half to be pretty much within the 10 ring, and about 1 in 20 to be a *** there's no way I shot that flier.

Federal 510 will just all be within the 9 ring with nothing much on call. I could never clean the rayvin target with HV. When I switched even to Wolf which is a waste of time because of the fliers, I cleaned it the first try.

Same thing on the SR target at 200. Never could clean it with HV cleaned it first try with Wolf.

I also had an opportunity earlier to shot Federal Gold Medal at Wolf Creek on the electronic targets at 50m until they ran out of it. I then switched to federal lightning (510) before I knew there was was a difference and shot scores that were maybe 95%-97% of what I was shooting with standard velocity.

There's really not that much difference. I really didn't notice a difference and at the time just chalked it up to the quality of the ammunition.

The was a lady at Wolf Creek who was an Czech Olympian and I think a world champion who shot 510 as her practice ammunition ( I'm sure it wasn't supersonic out of the free pistol ) so I don't think there was that much difference in quality.

Whether HV is suitable or not is really dependent on what you're using it for. I'm sure in a lot of cases it's a better choice but for pure accuracy not so much.

Last edited by landshark; 02-26-2017 at 12:47 PM.
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  #9  
Old 02-27-2017, 01:51 AM
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Some other stuff

"landshark" Thanks for the clarification. Not many folks call their shots at the shot anymore. Seems to be a lost art.

Gonna be my last post but I think it adds something to the accuracy equations.

Again, I am not a ballistician so what follows are what I have learned from our customers during the time the company I ran made capital equipment for both the civilian and military markets that either were Military armory's or folks like Remington.

There are a number of factors that have more negative impact on accuracy then the trans sonic effects.



Like most "global" statements one of the most often stated is that target ammo is more accurate because of the quality control. True but maybe a tad to broad although I can't think of a better one.

The "target" folks also design bullets to optimize the relationships between the center of gravity, center of pressure and the bullet's longitudinal axis.

Number of ways you can do that. Driving band width's, their position on the bullet, and especially if a bullet is "waisted" as you can see here:



Even a very small difference in circumference near the center of gravity reduces of the 3 main factors, especially nutation, of the bullet during flight.



Folks working on the Bell X1 Rocket plane had almost unrecoverable control problems when it transitioned to above the speed of sound until they hired a civilian engineer who "clued" them in about having a "waist" on the aircraft.

I believe his name was Whitcomb.

Until the advent of engines that generated more thrust then the weight of aircraft going straight up, and more sophisticated controls, a "waist" was used. Still used in low cost fighters.

With a heeled bullet, if you design it correctly and then manufacture it correctly, you can create a "waist" behind the driving bands, or at least that was what I was told by some real ballisticians.

So while the overall quality of the round is better due to quality control, the performance is also better due to bullet design and the tooling and quality control for that, which requires more precise, read expensive, capital equipment expenses and adherence to specs.

Again, I am not saying that the transition between supersonic and subsonic conditions does not occur or that the result does not adversely affect accuracy.

What I am saying though is that using that as a global statement for measurable variances in "groups" is way too generic. IMO and again IMO, it is too easy an answer to a complex question.

noremf(George)

Last edited by noremf; 02-27-2017 at 05:37 AM.
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Old 02-27-2017, 08:38 AM
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To me "calling the shot" refers to the shooter calling the shot based on where his crosshair was when the round ignited, without looking at the hole or being told where he hit.

With .22 LR through a scope I can clearly see the bullet going downrange, esp. with lower magnification where your field of view and depth of field (focus) are greater. Shooting, I recover from the recoil just in time to see the bullet fly they final 20% or so of the distance.

However, while seeing that clearly, whether spotting or shooting, I cannot tell where it is going to land because the arc of the trajectory is so great, and small inconsistencies in the cartridge, wind, etc., make the round hit higher or lower than you think they were going to based on what you saw. I can see if a bullet is off left or right while it is in flight, but I can't tell you where it is going to land up and down, unless it is way off, of course.

Anyway even with slow, match ammo it happens too fast to call out "Left" or "Right" before the bullet lands. I want spotters to tell me exactly where the bullet landed, not what they thought they saw while it was in flight, even though they often will have seen pretty well what was about to happen based on seeing the bullet travel downrange.
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  #11  
Old 02-27-2017, 07:02 PM
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Well this was sure interesting, enjoyed the read. Thank you all for sharing.
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  #12  
Old 02-27-2017, 07:54 PM
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Sure does make you wonder how we can hit anything out yonder and beyond.

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Old 02-28-2017, 02:04 PM
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In theory...

The old saying, " In theory, theory and practice should be the same, in practice they're not."
When Federal first started making it's UM1 and UM1B I was shooting a lot of 100, 200 yard benchrest matches at our club. While the theory says that the UM1B, which was sub sonic should have performed better than the super sonic UM1, my rifle didn't see it that way. To this day neither Eley nor Lapua shoot as well as the old UM1 did in that particular rifle at 200 yards. With .22's it's always what the rifle likes that matters. Now I will say that that rifle is the exception among my target guns as all the others prefer standard sub sonic match ammo.
Of course the other big problem with super sonic .22's is finding a true match grade product to test at long range.



Dennis
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Old 02-28-2017, 05:28 PM
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.22 non-magnum rimfire

Quote:
Originally Posted by Topstrap44 View Post
Sure does make you wonder how we can hit anything out yonder and beyond.

Topstrap
Sure does. Many ballisticians marvel at the performance of the .22 non-magnum rimfire rounds.

Reminds me of the F4 Phantom. They just kept adding bigger and more powerful engines to it to get it off the ground. Mathematically it should have never flown worth a flip, even with the added power.

Was known in Viet Nam as the "Brick that flies". The the guys with the big watches loved em.

noremf(George)
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