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  #31  
Old 05-20-2019, 10:05 PM
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Originally Posted by NDTOO View Post
That's a good observation however those bales will never be fed to my livestock and will be burned after they have served their purpose.
Ok thanks , wondered about that problem I have is stock have access to my range so would need to fence off the bales. Would be cheaper to use bales than doze up earth I guess tho round bales selling in some parts of oz up to $170 au due to drought I average aby 300 - 400 bales per year.
Cheeers and thanks ron
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  #32  
Old 05-22-2019, 08:13 AM
plumas
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Check this out.

https://www.accurateshooter.com/guns...mparison-test/
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  #33  
Old 05-22-2019, 09:19 AM
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Very interesting, but as they say, "Your mileage may vary."
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  #34  
Old 05-22-2019, 09:51 AM
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Originally Posted by plumas View Post
That's interesting.

I picked four that had similar performance at 50 and compared the groups at 100. the third number is the 50 yard measurement divided by the 100 yard measurement.

Federal Champion .356 1.032 .344
Eley SS HP .362 .952 .380
CCI MiniMag. .371 1.1 .337
Federal Gold Medal .398 1.142 .348

If turbulence were a significant variable, MiniMag and Champion should be trainwrecks. They are slightly worse than their subsonic 50 yard peers, with the largest difference in the third number between CCI and Eley with a number 12% better than CCI.
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  #35  
Old 05-22-2019, 11:13 AM
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Reading that chart there are some real surprises regarding which ammos I would have guessed would have come out on the top portion of the list and which would have been on the bottom.
For instance, T22 was solidly in the middle of the list but SK Standard was near the bottom...

Maybe this doesn't really prove much at this point but it seems the "high velocity transition" is much ado about nothing unless you are competing where every thousandth counts... It would be interesting to see this test stretched out to 150-200 yards, but I'm not sure the results would be much different.

This still shows that every rifle and ammo combination is different, even when shooting the highest grade rifles and the highest grade ammos.... test in your rifle is still the best advice.

Bob
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  #36  
Old 05-22-2019, 11:55 AM
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Maybe this doesn't really prove much at this point but it seems the "high velocity transition" is much ado about nothing unless you are competing where every thousandth counts...
I think that bears on Jaia's point earlier. Even if transitional turbulence is a problem, one still wants the ammunition that provides the best groups, not the least degradation over distance.

I can understand a benchrest shooter worrying about hundredths of MOA at any distance, but that benchrest shooter is still going to want the most accurate round rather than the round that doesn't endure transitional buffeting. If CCI SV shoots a half inch at 50 and 1.2 inches at 100, and MiniMags shoot a quarter inch at 50 and one inch at 100, then MiniMag is a more sensible choice even considering its greater degradation post transition.

Last edited by zukiphile; 05-22-2019 at 12:28 PM.
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  #37  
Old 05-22-2019, 12:20 PM
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Yep I agree with all these posts.

Like shoes, we may share a size 9 but one brand just feels better than another.
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  #38  
Old 05-22-2019, 01:34 PM
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Years ago we had a 100 yard best group match. You shot as many targets as you wanted and sent the best t0 Joe Haller for measurement. Although the data is probably still on the forum it may be hard to find. I compiled the results, rifles used, scopes used, ammo used and group sizes. I thought you might want to see what real world results look like as opposed to keyboard groups. Remember, there are cherry picked groups, not shot on demand. I competed in 100 yard group matches for a number of years and by and large, the group sizes were in the same sort of range. Winning groups ran from low .3s to high .4s and all the rifles were benchrest quality and the ammo was always high end Eley or Lapua.
Here is the group size distribution:

And here is the ammo used. I believe some was HV ammo and I'm certain that their groups sizes were at the high end
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  #39  
Old 05-22-2019, 02:57 PM
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That test is only valid for that specific gun and those specific ammo lot numbers, on the specific day tested.
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  #40  
Old 05-24-2019, 05:54 AM
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If a person wants to know if transition buffeting is a factor why not measure it???

Today we have things called chronographs. We have well established tables delineating the speed of sound change at various altitudes so that we can establish speed of sound at a given altitude and air pressure accurately.

Set up the chronograph and establish a target placement down range at a distance to eliminate the velocity variance of the ammo so that all shots fired on the the target are above the speed of sound. Set a second target target down range where all shots fired on it are now below the speed of sound.

Tested thus, even a moderately accurate rifle will show some difference if enough shots are fired and there is in fact transition buffering with that ammo. It may not be enough to show the difference shot to shot with the accuracy of a given rifle. (the rifle may not be accurate enough that it swamps out the buffering variance). But there should be a lot of rifles that are that accurate and then it becomes a matter of shooting enough rounds to see if tere is a difference.
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  #41  
Old 05-24-2019, 07:15 AM
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Eliminating variables when testing.

The idea of testing transitional instability is a good one. If the ranges of the targets vary, another variable is introduced and throws the results into question. The targets really should be at the same distance and allow the high velocity rounds to arrive at supersonic speed and the low velocity rounds must start out at subsonic speeds. One of the problems is that the targets will need to be pretty close which makes calculating group size difficult. One chart I looked at had the CCI Mini-Mag dropping below the speed of sound before reaching 50 yards. Still supersonic at 25 yards, so maybe if you can test at that range.

http://www.shooterscalculator.com/ba...php?t=4bccf14b
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  #42  
Old 05-24-2019, 07:24 AM
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Wind deflection, 100 yards, .17 HMR versus .22 40 gr. sub-sonic.

Wind deflection at 100 yards with the .17 HMR is 3.06 inch.

http://www.shooterscalculator.com/ba...+Create+Chart+

The wind deflection at 100 yards of the 40 gr. sub-sonic is 3.69 inch.

http://www.shooterscalculator.com/ba...php?t=eeceec81
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  #43  
Old 05-24-2019, 10:41 AM
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Originally Posted by David Valdina View Post
The idea of testing transitional instability is a good one. If the ranges of the targets vary, another variable is introduced and throws the results into question. The targets really should be at the same distance and allow the high velocity rounds to arrive at supersonic speed and the low velocity rounds must start out at subsonic speeds. One of the problems is that the targets will need to be pretty close which makes calculating group size difficult. One chart I looked at had the CCI Mini-Mag dropping below the speed of sound before reaching 50 yards. Still supersonic at 25 yards, so maybe if you can test at that range.

http://www.shooterscalculator.com/ba...php?t=4bccf14b
In all probability it will take a lot of rounds, hundreds, and maybe hundreds of groups to establish a pattern that may only amount to something as small as .010 or so difference. Perhaps, a very accurate rifle would cut the number of groups down enough to be.

I have a very accurate 52 with a bull barrel on it which at 28 inches might be just enough to launch something like eley target ammo just suoersonic, but that begs the question would ammo designed to be just subsonic be as accurate or would it be worse at just supersonic speeds? Also, there is the possibility that ammo that exceeds the speed of sound by a wider margin be more or less likely to show instability passing through the barrier. ie: it may spend more or less time during the period of instability, and it may be that the time spent being less stable is more important than the velocity.

A properly designed experiment would not be as easily set up as may be supposed, and it may very well turn out that several iterations of testing may be necessary to determine which parameters are necessary to highlight most accurately the issue of transonic stability.
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  #44  
Old 05-24-2019, 10:58 AM
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I guess each person can set up this testing as scientifically or unscientifically as they choose but the one thing that keeps gnawing at me is this- after all the talk about the supersonic transition, how much does it really affect accuracy at certain distances? If we're only talking a few ten thousandths it is hardly worth considering, except for perhaps serious bench shooters.

Knowing you velocities at the muzzle and at the 100 yard mark can be pretty fairly deduced from printed information already available but setting up your chrono at different distances to measure for each change of ammo may be worthwhile to you- or not.

When all is said and done we are still down to the same question we always seem to have on this site- which ammo shoots best in our particular rifles? And, should I try different ammos that I have avoided in the past due to "supersonic transition effect"? Depending on your requirements I would think this can be as simple or as complicated as you want to make it... but I do hope everyone shares their information so there is some benefit to the group..

Bob
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  #45  
Old 05-24-2019, 01:14 PM
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Rule of thumb, 16" barrel gives highest velocity.

Rule of thumb, a 16 inch barrel will give a standard .22 long rifle bullet the highest velocity. Powder/gasses have finished expansion and thereafter barrel friction slows the bullet. If you have a chronograph shoot your ammo with a target pistol, the shortest rifle barrel and the longest and look at the results.

And back to reducing variables, match ammo is made with a higher QC than high speed ammo. All of the benchrest shooters are using match ammo. None use high speed ammo. Shooting 50 yards the transition from supersonic to subsonic would take place. So how much of the results are due to that and how much due to QC ?

I believe the centerfire bench shooters like high velocity though out the entire range they are shooting and experience poor results if the rounds go sub-sonic before reaching the target.
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