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Campfire Ranger
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Don’t think I’ve ever seen a parabolic natural log. The ones I see tend to be pretty straight or bowed in the middle.
Regarding the wind. A 12 or 1 o’clock wind would be pretty straight on too. Wouldn’t think it would have much effect.
But math was never my strong point A wind from 11:00, 1:00, 7:00 or 5:00 is 30 degrees off so crosswind effect would be half that of the same wind from 3:00 or 9:00.
NRA Life,Endowment,Patron or Benefactor since '72.
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Campfire Ranger
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Campfire Ranger
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Biggest effect I've experienced on causing lateral (horizontal stringing) off the bench is not having the rifle fore-end centered in the front rest, causing intermittent horizontal stringing.
Ed
"Not in an open forum, where truth has less value than opinions, where all opinions are equally welcome regardless of their origins, rationale, inanity, or truth, where opinions are neither of equal value nor decisive." Ken Howell
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Joined: Jul 2007
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Campfire Ranger
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Campfire Ranger
Joined: Jul 2007
Posts: 24,657 Likes: 5 |
I fired two five shot groups at 300 yards. One was 2 3/8" and the other was 2 11/16". Both were about 1" vertical dispersion. There was a slight 1 o'clock to 12 o'clock breeze. Anyone know what causes it? I just might have a answer to this mystery A friend wrote this elsewhere, and I have slightly modified it for the question at hand...When shooting at 300 yards with a centerfire weapon, integrating the differential of the function's parabolic natural log means that exponential growth in the ballistic coefficient still amounts to less change in the Coriolis factor impacting wind shift than imparted y the longitudinal tidal force on the perfect sphere on a frictionless plane before imparting the subdural hematoma via hydrostatic shock on the bullet changing horizontal impact at 300 yards. 😀😀😀
WWP53D
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What time of day did you shoot? If the sun was out with a slight breeze mirage would open up the group. If it's a known load your shooting I would lean toward you were getting a weather report instead of a load report! Other causes would be seating depth, rifle needs cleaned, scope giving up, your not a good shot, etc
Good bullets properly placed always work, but not everyone knows what good bullets are, or can reliably place them in the field
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Joined: Sep 2022
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Campfire Member
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Campfire Member
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Maybe the gravity wasn’t Continuously pulling the same during your shooting session, fluctuations can cause vertical strings.
My sock puppet has a sock puppet!
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Government is like a baby: An alimentary canal with a big appetite at one end and no sense of responsibility at the other. - Ronald Reagan
For why should my freedom be judged by another man's conscience? - 1 Corinthians 10:29
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Campfire 'Bwana
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Campfire 'Bwana
Joined: Aug 2010
Posts: 48,200 Likes: 23 |
I try to stick with the basics, they do so well. Nothing fancy mind you, just plain jane will get it done with style. You want to see an animal drop right now? Shoot him in the ear hole. BSA MAGA
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New Member
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While the parabolic natural log calculations have merit, a much larger effect on vertical dispersion is the vertical wonkiness factor or VWF. When it approaches infinity the rotational portion of projectile repeatability increases exponentially, and may have influenced the results observed by the shooter at 300 yards. To complicate matters, the VWF and HWF (horizontal wonkiness factor) interactionally inversely influence each other, forming the total tangential wonkiness factor, TTWF. When TTWF approaches 1.0000000 use extreme caution as point of impact could be almost anywhere, and the group size approaches infinity.
Another force may be in play here as well; the trigger spring twanger tension, TSTT. It can be influenced by any number of things such as the change in density, viscosity, shear force etc. of the lubrication in the mechanism, relative expansion/contraction in the steel, aluminum, plastic parts, and more. All of these are sensitive to temperature, pressure, dew point, phase of the moon, velocity of the trigger pull, and general wiggling around on the bench. A simple example of this is flicking a booger off your finger (the spring twanger) where the viscosity and stickiness can dictate success or failure to launch the projectile in a particular direction and hit the target in the intended location. Groups....forget it! Especially without a good rest.
The math involved in the calculations is expansive, and would have given Albert Einstein indigestion or worse. Where is Stephen Hawking when we need him most?
My math is VWF + HWF + TTWF + TSTT = 100% BS
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Horizontal is tuned out with seating depth during load development. Seat the bullet in .005 increments away from the lands until you see the load go horizontal and then you’ve went too far. If it’s factory ammo, nothing you can do without a barrel tuner. It can be trigger puller induced also which would be the first thing to try and rule out.
Last edited by jsthntn247; 11/22/22.
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Campfire Outfitter
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It may help to sacrifice a small animal, like a rabbit or a chicken, to the gods of horizontal dispersion. Works for me. I sacrifice hundreds of small animals a year.
I belong on eroding granite, among the pines.
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Joined: Jun 2008
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Campfire Member
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Campfire Member
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Horizontal is tuned out with seating depth during load development. Seat the bullet in .005 increments away from the lands until you see the load go horizontal and then you’ve went too far. If it’s factory ammo, nothing you can do without a barrel tuner. It can be trigger puller induced also which would be the first thing to try and rule out. ^^^This!^^^ I had the same problem with a 7mmRM last year. Great groups vertically but pretty much two separate groups, separated horizontally. Anyway, somebody on some form said that adjusting the seating depth should correct it and it went from 1.5MOA to 0.5MOA.
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Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2006
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There was a slight 1 o'clock to 12 o'clock breeze. Anyone know what causes it? Yes, air masses of differing temperatures seeking equilibrium. During the day, air above land heats up faster than air above water. Warm air above land expands and rises, and heavier, cooler air rushes in to take its place, creating wind. At night, the winds are reversed because air cools more rapidly over land than it does over water.
A wise man is frequently humbled.
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Yall are funny. Coriolis and 300 yard groups. 2 inches? Lol. Nut loose behind the trigger. 2 inch group at 300, I'm happy, lmao.
Last edited by Coyote10; 06/10/23.
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What Ernie and onebackcast said,I might add that environmental issues are a major variable in the group size as is the shooters ability to read such........
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Campfire Tracker
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Campfire Tracker
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The shooter. You weren`t shooting the conditions, but just shooting.
Last edited by CGPAUL; 06/10/23.
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Campfire Tracker
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Good example of Horizontal springing. Notice the wind direction.
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Campfire Tracker
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On serious note. Is Vertical stringing is due to powder charge?
All of them do something better than the 30-06, but none of them do everything as well.
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Campfire Ranger
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Campfire Ranger
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Mostly blamed on velocity variation, which can be due to several effects. Charge, cartridge neck issues, inconsistent OAL.
1Minute
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For once i think you might have nailed it Ernie. lol
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