Range Report Question on Spin Drift experiment

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Dthomas3523

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    • Jan 31, 2018
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    #1
    So, people are always going back and forth on spin drift and how much it is in real life vs calculators. How much it matters at 1k, etc.

    Has anyone ever experimented say in a warehouse that is 1k yds with a rail mounted or secured rifle?

    Obviously finding an empty warehouse that long isn’t easy, but not impossible.

    Seems like it would put all of the debate to rest. It either lines up or it doesn’t.

    Also seems like something someone like AB would have already done.
     
    #3
    #5
    Sheldon N said:
    I think Litz or AB did a side by side with matching left twist and right twist barrels fired simultaneously. That said I still think AB engine over estimates spin drift, I back the twist rate off in my Kestrel until SD works out to about 0.2 mils at 1k yards.
    Click to expand...

    That’s an awesome idea.
     
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    #6
    Dthomas3523 said:
    Just skimmed it. Didn’t see where they did any actual testing that would ultimately prove the equations.
    Click to expand...

    Because it’s not a place but a what, which is mentioned in the article. I didn’t link that for you to figure out where, but rather how these things are done, and what goes into it. Sierra has a 300 yard underground range that was used for testing, I don’t know of any place to get 1000y controlled environment. If you want to know more about the specifics as to the linked experiment, you can try to message the guy that wrote it. He’s on here. There’s threads on it on here as well that go into great detail, and as to why there are different theories on how to calculate spin drift and why the numbers vary. That’s a starting point.

    You can’t say that shooting in a controlled 1000y range will end the debate if you cant rule out that different bullets, to different twist will act differently per a particular cartridge. It’s not that simple.
     
    #7
    Matches Malone said:
    Because it’s not a place but a what, which is mentioned in the article. I didn’t link that for you to figure out where, but rather how these things are done, and what goes into it. Sierra has a 300 yard underground range that was used for testing, I don’t know of any place to get 1000y controlled environment. If you want to know more about the specifics as to the linked experiment, you can try to message the guy that wrote it. He’s on here. There’s threads on it on here as well that go into great detail, and as to why there are different theories on how to calculate spin drift and why the numbers vary. That’s a starting point.

    You can’t say that shooting in a controlled 1000y range will end the debate if you cant rule out that different bullets, to different twist will act differently per a particular cartridge. It’s not that simple.
    Click to expand...

    Obviously if you took the time to arrange an indoor range, you wouldn’t limit the testing to one twist and one bullet type. That would be a waste of time.

    But several types of combinations would easily tell you if the calculations and theories are correct (or at least very close) as they would be pretty close to the calculated numbers.
     
    #8
    Dthomas3523 said:
    Obviously if you took the time to arrange an indoor range, you wouldn’t limit the testing to one twist and one bullet type. That would be a waste of time.

    But several types of combinations would easily tell you if the calculations and theories are correct (or at least very close) as they would be pretty close to the calculated numbers.
    Click to expand...

    I understand you’re argument, and what you are tryin to say, but what I’m saying is simply getting a cheat answer is not there, or it will/would have been published all over here and the various other forums, and we’d just use those pre-published legit and verified numbers, and there wouldn’t be a debate because it would be correct. Beyond that, even if there was a published and verified spin list per bullet per cartridge per twist, it’s the Internet. Ignorance and and man child retards are still out there.

    Closest you got is using 2% for non monos. Seems to line up with me, and a lot of other peoples spin dope, the math and logic seem sound. Bryan litz’s formula probably work well with his Berger bullets. Maybe one day, someone will make a 1000y controlled range, but in the mean time, they shoot at 1-300 yards and measure the results and mathematically calculate/predict what the results at distance with their big brains after using computers and models.
     
    #9
    It would be nice to have the data for general knowledge. I completely neutral environment would be impossible, especially out to 1000 yards/meters, but worthy of a study with all equipment parameters explored.
     
    #10
    Matches Malone said:
    I understand you’re argument, and what you are tryin to say, but what I’m saying is simply getting a cheat answer is not there, or it will/would have been published all over here and the various other forums, and we’d just use those pre-published legit and verified numbers, and there wouldn’t be a debate because it would be correct. Beyond that, even if there was a published and verified spin list per bullet per cartridge per twist, it’s the Internet. Ignorance and and man child retards are still out there.

    Closest you got is using 2% for non monos. Seems to line up with me, and a lot of other peoples spin dope, the math and logic seem sound. Bryan litz’s formula probably work well with his Berger bullets. Maybe one day, someone will make a 1000y controlled range, but in the mean time, they shoot at 1-300 yards and measure the results and mathematically calculate/predict what the results at distance with their big brains after using computers and models.
    Click to expand...

    Then the simple answer is “no, no one has put any of this to a test with as little environmental factors as possible.”

    Now, the question is, has no one done it because it’s not a viable test, or just because no one has done it?

    Much of the things that haven’t been tested in the firearms industry is because no has taken the time or has the means/money to do it.
     
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    #12
    Read this about a group of people that tried to remove "environment" from ballistics....

    precisionrifleblog.com

    Secrets of the Houston Warehouse – Lessons In Extreme Rifle Accuracy

    Back in 1993, Precision Shooting Magazine printed a landmark article about the findings of a group o...
    precisionrifleblog.com precisionrifleblog.com

    Most interesting thing to me is that they came up with a "Golden Means" for barrel length - 21 and 3/4 inch - it was determined to be the exact length to produce accuracy.
     
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    #13
    Are we talking high BC 6mm bullets, or bullets in general? The 6mm bullets we shoot have little movement compared to light 7mm hunting bullets, or shitty 6.5 hunting bullets. The larger the dia of the bullet, the more spin drift there is.
    I get to shoot on what one would consider dead calm days a lot(retired), plus I am around a lot of hunters trying to pull off the shot of the century with crappy bullets. Example, one day some idiot zeroes his 7mm-08 2" left of bullseye, 140gr bullet, we have chrono numbers, tell him to shoot a dot on steel at 500. Impact low but 10" right for 2 shots. All of us shooting 6mm's were holding .1 to center.
     
    #14
    Any and all.

    Software makes predictions for all kinds of bullets.

    The issue is many people claim the software overstates the observed spin drift. So, common practice elsewhere is to test the theories/equations. If the outcome is consistently different than predictions, it’s back to drawing board to figure out why.

    Basically, the difference between theoretical and experimental specialities within a field of study.

    Way to much theoretical and/or anecdotal stuff out there on ballistics and not enough real data.

    Obviously most of it is due to logistical/financial resources being hard to source for stuff like this. I’m just asking if anyone has attempted it.
     
    #16
    THEIS said:
    Hi,

    I am game for this :).
    Let me find the longest indoor tunnel I can find and we will coordinate such.
    I am with you that nothing is known for certain until it is proven or disproved in a controlled, documented and repeatable process.

    Sincerely,
    Theis
    Click to expand...

    If your doing all that, might as well rent an industrial fan running near the muzzle and test AJ
     
    Last edited:
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    #18
    MCHOG said:
    You don't just need a tunnel or a building long enough. You need it to be tall enough for your max ord at the distances where spin draft matters. That would be a tall order. Pun intended.
    Click to expand...


    Yep. was thinking about that earlier today..........

    Otherwise Reinforced Concrete pipe comes in 8 foot lengths, something like 375 lengths of pipe could give you a 1000 yard environmentally perfect range.

    Guess we will get to use pipe tunnel ranges when "Freaking Lazers" are in common useage.
     
    #19
    MCHOG said:
    You don't just need a tunnel or a building long enough. You need it to be tall enough for your max ord at the distances where spin draft matters. That would be a tall order. Pun intended.
    Click to expand...
    Not too many bullets would need over 20 feet. 75gr 223 bullet at normal speeds only needs 15 feet.
     
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    #22
    Milo 2.5 said:
    Give me your load, I am at 15'.
    Click to expand...

    Just simulated. Not the actual load data. I don’t use this app. Going off max ord at 60% of total range.
     

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    #23
    Unfortunately it's difficult to compare against indirect-fire (artillery) drag models that utilize 6-DoF or even 7-DoF (BALCO) versus fixed drag "G" models. This is unfortunate because there is a lot of data in that area - although it seems to be acceptable using those models against NATO 7.62 168g bullets (see attached) in this one publication that I could find.

    The basics:

    A) Projectile length - Longer = higher rate of drift
    B) Twist Rate - Higher twist = higher RPM = higher rate of drift
    C) Atmospherics - Lower DA = higher rate of drift
    D) Flight time - Longer = more time, more drift

    There's just many variables to figure in though. The results of a real-world test versus synthetic are likely to fall within the noise-floor, outside of the controlled environment I doubt it would ever matter as wind will never be absolute zero. This isn't even factoring in the annoying little things like Magnus and Poisson (also assuming the test range is perfectly off of a parallel by 23.5 degrees in order to avoid Coriolis drift horizontal effects tainting the test results - firing on the orbital plane).

    Would definitely be a neat test to perform. I'd like to see it performed in a "tunnel", as well as an open range using doppler to gather exact wind data in real-time.
     

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    #24
    Hi,

    The open range testing was and has been done decades ago at Yuma....it was the "scientific" basis of the reduced spin drift patent of the original Cheytac & Associates (Not the modern Cheytac company).

    The tunnel couldn't be at the minimum size requirements based on the ballistics alone, it would have to be large enough volume that it was immediately render the argument of "spiked air pressure" and "muzzle blast ricochet", etc etc etc caused a disruption/disturbance/etc

    I searched for locations briefly last night but an indoor ones has not been found.....

    NASA AMES facility is not long enough.
    Rheinmettals' test facilities are not long enough (outdoors they are).
    RUAG test facilities are not long enough (outdoors they are).
    Denel Overberg Test Range facilities are not long enough (outdoors they are).

    Sincerely,
    Theis
     
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    #25
    THEIS said:
    Hi,

    The open range testing was and has been done decades ago at Yuma....it was the "scientific" basis of the reduced spin drift patent of the original Cheytac & Associates (Not the modern Cheytac company).

    The tunnel couldn't be at the minimum size requirements based on the ballistics alone, it would have to be large enough volume that it was immediately render the argument of "spiked air pressure" and "muzzle blast ricochet", etc etc etc caused a disruption/disturbance/etc

    I searched for locations briefly last night but an indoor ones has not been found.....

    NASA AMES facility is not long enough.
    Rheinmettals' test facilities are not long enough (outdoors they are).
    RUAG test facilities are not long enough (outdoors they are).
    Denel Overberg Test Range facilities are not long enough (outdoors they are).

    Sincerely,
    Theis
    Click to expand...
    Outside of the obvious spacial requirements required to test ballistics, Yuma has another unintended benefit.

    In that area, as the sun goes down, and thermals start to calm down, there is very often an almost eerie quiet. There is a county owned 1,000 yard range (Adair Range) that is high bermed on both sides and faces due North. When this condition exists, you can literally throw moon dust in the air and it will not drift. It just floats in place as a cloud for a bit.

    This place is, at the right times, as good as indoors. It is available just about every day, and it's free.
     
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    #26
    Skookum said:
    Outside of the obvious spacial requirements required to test ballistics, Yuma has another unintended benefit.

    In that area, as the sun goes down, and thermals start to calm down, there is very often an almost eerie quiet. There is a county owned 1,000 yard range (Adair Range) that is high bermed on both sides and faces due North. When this condition exists, you can literally throw moon dust in the air and it will not drift. It just floats in place as a cloud for a bit.

    This place is, at the right times, as good as indoors. It is available just about every day, and it's free.
    Click to expand...

    That period of evening you describe is also the perfect lake fishing time in my opinion.
     
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    #28
    THEIS said:
    Hi,

    The open range testing was and has been done decades ago at Yuma....it was the "scientific" basis of the reduced spin drift patent of the original Cheytac & Associates (Not the modern Cheytac company).

    The tunnel couldn't be at the minimum size requirements based on the ballistics alone, it would have to be large enough volume that it was immediately render the argument of "spiked air pressure" and "muzzle blast ricochet", etc etc etc caused a disruption/disturbance/etc

    I searched for locations briefly last night but an indoor ones has not been found.....

    NASA AMES facility is not long enough.
    Rheinmettals' test facilities are not long enough (outdoors they are).
    RUAG test facilities are not long enough (outdoors they are).
    Denel Overberg Test Range facilities are not long enough (outdoors they are).

    Sincerely,
    Theis
    Click to expand...
    We need that Houston Warehouse again !
     
    #30
    THEIS said:
    Hi,

    Except that 325 yards does not do shit for the distances needed for this test to be useful, lolol

    AMES facility is 466 yards and has enough wind generators to push projectiles any direction, but it is not long enough either.

    Sincerely,
    Theis
    Click to expand...
    Agreed. For some reason I thought it was 500 or a bit longer. There were some cool experiments done there though.
     
    #34
    THEIS said:
    Hi,

    The open range testing was and has been done decades ago at Yuma....it was the "scientific" basis of the reduced spin drift patent of the original Cheytac & Associates (Not the modern Cheytac company).

    The tunnel couldn't be at the minimum size requirements based on the ballistics alone, it would have to be large enough volume that it was immediately render the argument of "spiked air pressure" and "muzzle blast ricochet", etc etc etc caused a disruption/disturbance/etc

    I searched for locations briefly last night but an indoor ones has not been found.....

    NASA AMES facility is not long enough.
    Rheinmettals' test facilities are not long enough (outdoors they are).
    RUAG test facilities are not long enough (outdoors they are).
    Denel Overberg Test Range facilities are not long enough (outdoors they are).

    Sincerely,
    Theis
    Click to expand...
    What about the cancelled supercollider tunnel in Texas (52 miles circumference and 14ft diameter) :)
     
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