How Much Does A headwind impact .223 ?

[hunter24605]

So shooting the 223 Rem yesterday with proven loads, I was shooting into a headwind that gusted between 10-15 MPH, I noticed the first few shots were hitting as expected but the last couple hit about 1.5" low...This happened with 2 different charges..The only difference was these were not crimped like the proven rounds were, but still the first shots hit where I expected them to and the last two always hit low..Like said the wind was gusting so perhaps by circumstance and coincidence the last two shots of each group were fired during a faster wind gust? Or perhaps the lack of a crimp allowed the last two to be fired to setback a little after firing the first two and making them hit low? I'm leaning towards blaming the wind rather than bullet setback in the mag, but opinions welcomed. These were 55 grain bullets being fired at 100 meters...I guess I should also mention there was a very light rain falling.

 

[hereinaz]

Crimp can affect pressure. Pressure affects velocity. Velocity affects drop.

If your crimp loads were the only low ones, then I would start there.

 

[hunter24605]

Crimp can affect pressure. Pressure affects velocity. Velocity affects drop.

If your crimp loads were the only low ones, then I would start there.

They were all un-crimped..I was testing them against crimped ones I fired a few days ago.

 

[mjcmichigan]

A 30mph wind is also a 440fps wind. I'm not a mechanical engineer or physicist, but I'd bet, if you gave them the speed of your round, weight, BC, they'd predict you'd be low 1.5"


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[hunter24605]

A 30mph wind is also a 440fps wind. I'm not a mechanical engineer or physicist, but I'd bet, if you gave them the speed of your round, weight, BC, they'd predict you'd be low 1.5"


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Kind of my thinking..I know rainy, snowy, windy days ain't much fun to shoot in, but you learn some interesting things!

Tomorrow is supposed to be nice, so I'm going to duplicate the loads and try again.

 

[hereinaz]

Crimp can affect pressure. Pressure affects velocity. Velocity affects drop.

If your crimp loads were the only low ones, then I would start there.

They were all un-crimped..I was testing them against crimped ones I fired a few days ago.

Crimping creates consistent neck tension. But, the environmental factors are probably greater here.

 

[joelkdouglas]

Wind can blow the shooter around too. Even when I am concentrating while shooting in the wind I wouldn't say it has no effect.


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[c. schutte]

A 30mph wind is also a 440fps wind. I'm not a mechanical engineer or physicist, but I'd bet, if you gave them the speed of your round, weight, BC, they'd predict you'd be low 1.5"


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excellent point.................. I came up with 44 fps for a 30 mph wind. I've got to admit that I am not as good with math as I was back in school though.......................... (and the case could be made that I was not all that good then too :shock: )


If that wind was only 10-15 mph then the fps speed would be even less, around 15-22 fps if I happen to get this one right? I would be inclined to think it had more to do with the crimp. Since pressure effects velocity that would make the bullets leave the barrel at different speeds which would also make them leave when the end of the barrel is at different points in the harmonic wave?

Anyway, not trying to be a smartarse, just trying to see if I followed the reasoning correctly.

Thanks..........chs

 

[hunter24605]

A 30mph wind is also a 440fps wind. I'm not a mechanical engineer or physicist, but I'd bet, if you gave them the speed of your round, weight, BC, they'd predict you'd be low 1.5"


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excellent point.................. I came up with 44 fps for a 30 mph wind. I've got to admit that I am not as good with math as I was back in school though.......................... (and the case could be made that I was not all that good then too :shock: )


If that wind was only 10-15 mph then the fps speed would be even less, around 15-22 fps if I happen to get this one right? I would be inclined to think it had more to do with the crimp. Since pressure effects velocity that would make the bullets leave the barrel at different speeds which would also make them leave when the end of the barrel is at different points in the harmonic wave?

Anyway, not trying to be a smartarse, just trying to see if I followed the reasoning correctly.

Thanks..........chs

Agreed. Very valid point. But like I said, All the bullets I fired that day were un-crimped..I would load 4 in the mag for each charge weight I was testing..The first two would hit where expected and the second two would hit low..I was firing a batch of un-crimped loads to compare the difference, if any, with the crimped loads I shot a few days earlier.

I had an epiphany of sorts last night....Maybe it isn't the fact that they were not crimped that was potentially causing them to setback in the case after a few rounds was fired, but rather I should be looking at neck tension..There could be something up with my FL die.

 

[Rocketvapor]

A headwind coming across the top of a berm/backstop can blow downward.
A little drizzle can also affect POI.

But, first 2 on target, second 2 always low does point to neck tension.
I hardly ever crimp .223.
I have polished down my Lee expanders for just over 0.002" tension.
I also use a turret press in single stage mode so I can feel seating force.
If it feels light it gets redone.
Give your bullet a good hard finger twist. Move?

 

[mjcmichigan]

Lol. Yes! 44 fps!
That's what I get for doing the math on a napkin on an airplane while talking too!!


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[hereinaz]

Are you saying that for the third and fourth cartridge the bullet "set back" in the case? Recoil affected OAL because neck tension is too loose.

 

[35 Whelen]

Well when you say headwind that takes in some interesting
Country...... Like alot of folks over the years I had a .223 because it was going to be "cheap to shoot" . I did alot of stuff with it around 300 yds. I used a 55gr bullet running about 3200fps. These numbers still stick in my mind a 15mph full wind is over 18" of horizontal error! And it got
Nuts behond that as 350yds its over 2ft and at 400yds it was over 3ft ! Which certainly helped with the dozens of misses on coyotes over the years.
So how far off an exact straight on headwind (which it would almost never be) 5 degrees off (would feel like a direct headwind in your face) will start to mess with you some ??? 25 degrees off , Which would probably still just be called a headwind , would be begining to become an error that at longer distances needs to be corrected for....... You may be able to pin it onto neck tensions or some other facet of reloading, but over the years we transitioned to the 22/250; because the shorter time of flight of 4000fps was soposed to fix all that. It did work better but not enough, So we then went in a different direction; And increased the bullet weight to 100grs via a .243, And that halved the error. Wind has always been the shooters biggest enemy and probably always will be.
Just for fun I just ran the numbers(Strelok) with your 15mph wind for the .223 w a 55gr bullet, and a 25 degree off an EXACTLY Head on wind , (again most folks would refer to that as simply a "headwind")Strelok said you will have a 3.5" error at 200yds.
Good luck
E

 

[hunter24605]

Well when you say headwind that takes in some interesting
Country...... Like alot of folks over the years I had a .223 because it was going to be "cheap to shoot" . I did alot of stuff with it around 300 yds. I used a 55gr bullet running about 3200fps. These numbers still stick in my mind a 15mph full wind is over 18" of horizontal error! And it got
Nuts behond that as 350yds its over 2ft and at 400yds it was over 3ft ! Which certainly helped with the dozens of misses on coyotes over the years.
So how far off an exact straight on headwind (which it would almost never be) 5 degrees off (would feel like a direct headwind in your face) will start to mess with you some ??? 25 degrees off , Which would probably still just be called a headwind , would be begining to become an error that at longer distances needs to be corrected for....... You may be able to pin it onto neck tensions or some other facet of reloading, but over the years we transitioned to the 22/250; because the shorter time of flight of 4000fps was soposed to fix all that. It did work better but not enough, So we then went in a different direction; And increased the bullet weight to 100grs via a .243, And that halved the error. Wind has always been the shooters biggest enemy and probably always will be.
Just for fun I just ran the numbers(Strelok) with your 15mph wind for the .223 w a 55gr bullet, and a 25 degree off an EXACTLY Head on wind , (again most folks would refer to that as simply a "headwind")Strelok said you will have a 3.5" error at 200yds.
Good luck
E

That certainly explains a lot..I wasn't sure if I was getting setback or not. It just seemed odd that the first couple would hit in the right spot and the last couple would be low. I loaded some more un-crimped rounds and shot them this morning and they grouped fine....I suppose it was just the wind and happenstance that it gusted while shooting the 3rd and 4th rounds in the magazine each time...Although, more likely is that on the first and second shot I subconsciously waited for a lull in the wind and not so much on the 3rd and 4th.

 

[35 Whelen]

Well of course folks that never really shoot long distances dont really get to consirned with all this. BC of the bullet, and TOF are the two big factors to helping to over come wind deflection. I have for years baited coyotes in front of our home out on the lake , I tryed different distances and found that 300 yds was about as close as I could place it or ,They simply would not come to it . Because this all takes place when the lake is frozen, and the predominant wind is NW the baits pretty much 90 degrees to the NW wind......15/20 kt winds are the norm here. But many nites when its Stormy 20/30 kts is more likely! I now am shooting a 25/06 and a Sierra BlitzKing 90gr bullet @ 3400fps. Using a MilDot reticule , I can quickly compute the drift at any time using my weather stations wind speed and direction off the Strelok App on my phone. It was tell me how much I need to hold to correct for the wind. Even though I would have less than half of the error you would with a 223 caliber , a full Mildot is a common amount of hold ,and 1.5 is certainly a common hold as well. 2 mils is not as common (30kts) but we have certainly shot them with that much drift before.
So to give you an idea how much that relates to you and your 223 at 300yds with just your 15 mph wind you had if it were a full wind(direct Xwind). Here is what Strelok says, your error is almost 18" and it would take 23 clicks on my scope to" dail it out" This is what it will look like: 1.5 Mil of correction at 9X would look like this to you.
I wish I could now superimpose a coyote on there for you
So you would see how far OFF the animal you would need to hold(18") to hit him! They usually always stand into that much wind, so for a shoulder shot your always holding the crosshairs way out infront of his chest , as your now holding the 1.5 Mildot on his shoulder NOT the crosshair its now compleately off the animal. Some guys
Just cant ever get used to that and prefer to dail the error
Out so they can hold the crosshairs right on the shoulder?
Both methods will work. If you double the wind to 30kts it
Is amazing how FAR off your holding.
Good luck
E

 

[brikwhitt]

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