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Old April 9, 2015, 05:56 AM   #1
Pond, James Pond
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How big of an issue would wind be?

I want to try out my new hunting loads tomorrow. My 100m range is NNW facing and has 10ft concrete wall around the compound. On the 100m range, the closest I could shoot to the wall is about 30m (100ft or so).
Forecast say 5m/s westerly cross wind.

I am wind illiterate at this stage, so I a) won't know how to compensate and therefore b) won't know how significant 5m/s is to a bullet trajectory.
Strelok suggests about an inch of lateral drift, but that does not take into account the walls.

Should I ditch (read postpone) my OCW accuracy test or is that acceptable? No scope zeroing, just checking for group size.
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Old April 9, 2015, 05:16 PM   #2
g.willikers
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It depends as much on how consistent the wind is, as well as direction and speed.
If there's pauses in the wind, like gusting, shoot when it dies down, between gusts.
If it's steady, then that helps, too, as all the shots should go to the same place.
The confusing part of wind reading is when it keeps changing in speed and direction.
Reading wind is an important part of shooting rifles.
You might as well go and get the experience.
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Old April 10, 2015, 12:49 AM   #3
Pond, James Pond
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Quote:
You might as well go and get the experience.
Ordinarily I'd agree but, given that I'm trying to establish my latest gun-specific load, I don't want the results to be skewed by wind, making my conclusions either hard to draw or plain wrong.
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Old April 10, 2015, 04:39 AM   #4
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What caliber are you shooting , what is the velocity, bullet weight and ballistic coefficient of the bullet? 5M is not very much, generally speaking I don't think it will skew your metrics much if at all but you don't have all the data points. You need to know the above info as well as is the wind steady, gusting, where is the wind (all ranges out to 100M?) as the bullet slows the wind will have more effect. All that said 5M isn't much.

Try this. http://m.hornady.com/ballistics-reso...ics-calculator

Last edited by 1stmar; April 10, 2015 at 04:50 AM.
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Old April 10, 2015, 07:13 AM   #5
Pond, James Pond
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Cal. .308
Weight and BC. 165gr/0.333
Velocity... ??? As it was a charge weight test, the velocity was changing.

As you can guess, I went ahead with it.

I'm sure the wind had some affect on results, but I still have solid groups to work with. All the same, the wind was fairly constant. It rose and fell now and again, but not what one would call gusty.

Generally, there was much more lateral spread than I am used to.

I'll cover the results in a separate thread.
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Old April 13, 2015, 12:34 PM   #6
Bart B.
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That bullet drifts about .08 MOA per mph (2mm per 1.6 kph) of unobstructed cross wind at 100 yards/meters.

With obstructions nearby, it's hard to tell unless you have a wind meter to measure the actual wind speed in the line of fire.
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Old April 22, 2015, 08:54 AM   #7
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I had today off and planned a range trip with some rim fires(several .22LR's and a .17HMR) and the .223. Just my luck if its not pouring rain we are in a "high wind advisory" or both.

The only high power rifles I can shoot I recently re-scoped or installed ghost sights so they are out of the question too. Sighting-in, in heavy wind, is almost a frugal effort and waste of expensive ammo.

Bummed out. Even the skeet/trap/clays range is closed today or I would do that.

Its 65 degrees, sunny and 30mph winds with gusts to 60mph
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Old April 23, 2015, 06:23 AM   #8
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Well I went to the range and it was a frugal waste of time. My Ruger American .17HMR was all over the place at 50yds. The .22LR's all shot well. I didn't even try to adjust anything in that wind, just plink and enjoy a spring day in the Blue Ridge mountains
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Old April 25, 2015, 03:37 PM   #9
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5 m/s is about 11 MPH. Probably won't push a .308 much but a .22 or the like it will. Wouldn't bother test shooting loads at 30 meters myself.
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Old April 25, 2015, 09:51 PM   #10
Jim Watson
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I have seen a lot of reports of testing with the big slow bullets of BPCR and the vertical spread taken as the figure of merit; the horizontal spread being ignored as largely due to wind and "cheek mirage."
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