Question: Shooting into the wind

[jkupper]

I just got home from a little practice trip. I am waiting for the turrets for my Huskemaw scope, but While I'm waiting I decided to print out a drop sheet from the data that I collected previously and go shoot using my "clicks" turret. 3 clicks per minute of angle is an easy enough adjustment.

I check my 200 yard zero, and it is spot on. I decide to start easy and check my clicks at 300. Again, dead on, with the proper wind hold.

I back up to 500 yards and start to see why doping the wind is so challenging. My drop was dead on, but I had 1 shot 2 inches left of center, 1 shot 1 inch right of center, and one shot 3 inches right of center. Good enough to kill a deer, but I need to practice more.

Finally, I back up to 700 yards, which was as far away as I could get where I was shooting this evening. To get to 700 yards I had to go way north and shoot back into the wind. I had previously been shooting across the wind. The wind was blowing between 7-13mph from the south. I put in the appropriate clicks and let my first round go. It hit 1 inch low of the target. I thought I may have pulled it, so I let two more go. They all landed in the same place, 1-3 inches below my target. This would have been 1 1/4-1 1/2 MOA low of center.

My question is this. Will a head wind slow a bullet down enough to cause this? If so, how much effect will a tail wind have?

Any help would be appreciated, especially since I am just getting started in this game. Thanks,

Joe

 

[rifletuner]

My question is this. Will a head wind slow a bullet down enough to cause this?

Yes, easily.

If so, how much effect will a tail wind have?

Equal, but opposite. A tail wind will push a bullet up.

Both these answers are generalisations, but are accurate in most cases. A sideways wind can also give you vertical, so don't think this only comes from head or tail winds.

 

[Bodywerks]

I disagree. Adding 10mph resistance to something going over 1,000mph produces a negligible effect during its 1 second flight time. Need proof? Plug it into a ballistics calculator. Between my 338 lapua and my 260 a 10mph headwind induces less than a half inch of drop on both at 700 yards.
My guess is your observed/recorded MV is off a tad. It won't show at shorter distances because the trajectory tends to be pretty flat at shorter ranges.
That or your BC is slightly off but I'd lean toward velocity.

 

[rifletuner]

I disagree. Adding 10mph resistance to something going over 1,000mph produces a negligible effect during its 1 second flight time. Need proof? Plug it into a ballistics calculator. Between my 338 lapua and my 260 a 10mph headwind induces less than a half inch of drop on both at 700 yards.
My guess is your observed/recorded MV is off a tad. It won't show at shorter distances because the trajectory tends to be pretty flat at shorter ranges.
That or your BC is slightly off but I'd lean toward velocity.

No, you are dreaming if you think head or tail winds have no effect on the bullets impact.

 

[cohunter14]

From everything I have seen, I have to agree with Body, the wind is negligible both from behind and into the wind. As he said, throw it in to a ballistics chart and you will see for sure. However, you can get wind drifts that blow up or down off of hillsides, etc depending on where you are shooting. Have you shot at 700 yards before and, if so, were your results different? I also agree that your calculated MV might be off...

 

[canderson]

If you were to make your intended smaller and try and be very precise you will notice the headwind tailwind effect. I have shot numerous times at 1000 yard f class matches. The f class target has roughly a 1/2 MOA bullseye (x ring). Trying to keep 20 shots in the 1/2 MOA center is very challenging with pick up and let offs from head or tail winds. The winds will move point of impact several inches at that distance. I am using Berger 105 hybrid bullets. These bullets have very good BC. I would have to think a larger heavier bullet may not move quite as much but will still move.

 

[Broz]

I disagree. Adding 10mph resistance to something going over 1,000mph produces a negligible effect during its 1 second flight time. Need proof? Plug it into a ballistics calculator. Between my 338 lapua and my 260 a 10mph headwind induces less than a half inch of drop on both at 700 yards.
My guess is your observed/recorded MV is off a tad. It won't show at shorter distances because the trajectory tends to be pretty flat at shorter ranges.
That or your BC is slightly off but I'd lean toward velocity.

From everything I have seen, I have to agree with Body, the wind is negligible both from behind and into the wind. As he said, throw it in to a ballistics chart and you will see for sure. However, you can get wind drifts that blow up or down off of hillsides, etc depending on where you are shooting. Have you shot at 700 yards before and, if so, were your results different? I also agree that your calculated MV might be off...

I agree with these two posts and will share this info from my 300 win with a 215 Berger @3035 fps. These calculations are from Bryan Litz Applied Ballistics program.

1000 yard shot and no wind has a dial up of 20.5 MOA
1000 yard shot with a 10 mph head on 12 o:clock wind needs 20.5 MOA
1000 yards shot 10 mph tail from 6:00 needs 20.4 MOA

Increasing to a 20 mph wind @ 1000
12:00 head wind 20.6 MOA
6:00 tail wind 20.4 MOA


So as you can see the difference is around .1 moa for a good bullet at 1000 yards and up to a 20 mph wind. I doubt even the best shooters could define a .1 moa (about an inch) at 1000 yards.

Now with smaller calibers and less effective bullets I would expect these differences to magnify and I would also expect the same as distance is increased as bullets slow.

Jeff

 

[jkupper]

Okay. .1MOA at 1000 yards is a lot different from what I had at 700 yards. My MV may have been off from my drop sheet, I get that, but wouldn't it have been off of the mark at 500 yards as well? Or, is the difference there small enough that it wouldn't matter much?

This was the first time that I shot the gun at 700 yards at home. I shot it in Wyoming last weekend at 950 yards, but I was gathering the information for my turrets and didn't rely on a drop chart, I just adjusted from what my spotters were telling me.

I'm planning to go shoot again this next weekend from the same place and see if the results are the same. I should have my BDC turrets in by next weekend to, and I can confirm that they are on.

I'm was shooting 168 gr. VLD's, so the BC is rather high, .617.

I think this is just going to take a lot of experimentation....which is fun!

Thank you all for the replies!

 

[jkupper]

Okay, today I went out and shot again just to confirm what happened yesterday. The temperature was identical to yesterday but the wind was a little different. It was angling across my line of fire, and it was blowing between 8 and 15 mph with gusts up to 20. I got set up to start, from the same place and the same target location I had yesterday. I shot twice just to confirm what happened yesterday, and guess what, both shots were about two inches low. I dialed 1 more MOA into the Huskemaw and let three more shot go down range. You can see the results. Here is my setup first.
And then a picture looking down range.
Finally a picture of my group, which is about 11 inches wide. A gust came up on my second shot. I've got to work on my windage, but the group is only about 1 1/2 inches from top to bottom which makes me happy, happy, happy!

 

[Bodywerks]

Now, if you happen to have been shooting over hills and valleys in that headwind you could have very well been effected by down drafts, which have a MAJOR effect on bullet trajectory.

 

[jkupper]

Now, if you happen to have been shooting over hills and valleys in that headwind you could have very well been effected by down drafts, which have a MAJOR effect on bullet trajectory.

Then I may need to go back over there when the wind is out of the north sometime and see if that changes my point of impact. I suppose there could have been a pretty good draft coming down my target hill and/or a decent updraft on the hill I was shooting from. Real world practice though right.

 

[RMulhern]

If you had been shooting 500-700 gr. all-lead cast slugs for 20 years at 1000 yards.....you'd know all about this!