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  #1  
Old 06-02-2016, 10:30 PM
trotterlg trotterlg is offline
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Default Please someone explain these Balistics to me

I know this is hard to believe, and I am not sure I do, but if you use any ballistic calculator you will see that identical 22 RF bullets, one running at 1,000fps and one at 1,300fps, the one running at 1,000fps will have less wind drift at 100 yards than the one running 1,300fps. How can this happen? The wind drift of the 1,000fps bullet will not be more than the faster bullet until the faster bullet is exceeding 3,000fps. I think my head may simply explode thinking of this. I did my calculations using a 20 MPH cross wind. Larry
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Old 06-02-2016, 10:38 PM
georgeld georgeld is offline
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Larry:
I think someone that don't know is trying to spread the green stuff (or is it brown??) on the field and you're trying to believe it. I've read the same thing and think it's BS too.
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Last edited by georgeld; 06-02-2016 at 10:40 PM. Reason: misc
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Old 06-02-2016, 10:50 PM
trotterlg trotterlg is offline
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Go the Hornady ballistics calculator and run the numbers, I think they may know a little more than I do about the subject. Larry
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Old 06-02-2016, 11:17 PM
Chickenthief Chickenthief is offline
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When a bullet goes faster that sound it creates a cone/shockwave thing and the wind affects that and that is transferred to the bullet. Ie. it has a larger "surface" for the wind to push on.
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Old 06-02-2016, 11:21 PM
trotterlg trotterlg is offline
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Funny thing about the calculations is that the drift keeps getting better (less) from 1,000fps down until the bullet is going 650fps, both well below the speed of sound. Larry
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Old 06-02-2016, 11:45 PM
ramos ramos is offline
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Wish Bryan Litz would hang out here sometimes. Guess we are just not quite 'VLD' enough to draw his interest.
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Old 06-02-2016, 11:48 PM
trotterlg trotterlg is offline
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Far as I see the effect is the same but sub-sonic and super-sonic, even across the line. I just totally do not understand it. Larry
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Old 06-03-2016, 12:49 AM
tim simbari tim simbari is offline
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As far as better wind characteristics down to 650 fps, I'd tend to doubt that.
As far as sub sonic being generally better than supersonic, well, that's well known, well documented and the basis for why so very much of the best rimfire match ammunition is sub sonic.
Essentially it boils down to the following: it is a well known fact that when a supersonic .22 round is fired, at some point down range, before target impact, it passes back to sub sonic and when that happens, the slug becomes unstable for a period, sometimes a lenghty period.
With much 22 benchrest shooting done at 50yds/50 meters high speed stuff gets unstable right before target impact....bad juju.
You want the slug to present the smallest side profile.
Along the same thinking, it is why there tends to be lots of different barrel characteristics as far as fewer lands/grooves going down to 2 groovers and MI barrels which are minimally invasive rifling using shallow engraving trying to reduce he coriolus effect which simply is the amount of vertical componant per measure of wind drift.
All fairly important when you're trying to hit a 1/32" dot, 25 times on a target at 50 yards.
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Old 06-03-2016, 01:14 AM
trotterlg trotterlg is offline
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How would you explain 650 fps having the same wind drift at 100 yards as 1,000 fps? All the calculators say it is true. Try it your self, 40 gr bullet, 20 mph cross wind, both the same drift. Larry
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  #10  
Old 06-03-2016, 02:02 PM
sgtg sgtg is offline
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Default sub to supersonic

one is subsonic. I ran the numbers on a 125 bullet .3 BC @ 1000 FPS and one @1300 and sure enough the 1000 FPS has less wind drift. ( 1.8 vrs 2.7 )
I know weird things happen when you go from subsonic to supersonic.
At sea level subsonic to supersonic is 1100 FPS. I think what your seeing is correct. Rocket science stuff. Send an email to Brian Litz @ Berger bullets. sgtg out
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