Wind effect

[dgcie]

Im just wondering.

A wind thats about 1-6 miles per hour (not a constant wind, just gusts every now and then). Would that have much effect on a 75 grain 223 at 200 meters.

Im looking at a grouping I shot yesterday and theres one or two bullets that seem to be sitting away from the rest of the group and I cant explain it so Im wondering could it have being the wind.

 

[kraigWY]

Re: Wind effect

Not much, I shoot 77 SMKs at 2650 and a 6 MPH wind only moves it less then 1 MOA.

 

[hrfunk]

Re: Wind effect

You didn't mention the specific bullet, muzzle velocity, or the deviation of the errant shots. Using a 75 gr. AMAX, at 2700 fps, I'm showing nearly 2 inches of wind deflection @ 200 yards if you happened to fire during a 6 mph gust.

 

[dgcie]

Re: Wind effect

Sorry I forgot to mention that.

Im using 75gr grain hornady TAP

Muzzle velocity is 3240fps
and at 200 yards its 2500fps.

BC is .255
SD is .157

My stray bullets were all off by around 1.5 inches though the worst was off by nearly 3 inches.

 

[Sterling Shooter]

Re: Wind effect

To understand the effect of wind you need to call your shots, as well as favor for wind and weather effects as they seem to be.

 

[Raptor 2-C-D]

Re: Wind effect

Try a balistic calculator. Iphone has an app called iSnipe you should take a look at. This will give you information on the effects on certine kinds of bullets, along with wind, rate of twist, angle of shot and ect.

 

[Sterling Shooter]

Re: Wind effect

The first thing you need to wonder is what caused the bullet to go somewhere other than where aimed. For example, if you call the shot 9 o'clock and indeed the strike is at 9 o'clock that means wind was not an issue. However, if you called the shot at 9 o'clock and discover the strike at 3 o'clock that could mean not countering for wind correctly. That's why it's important to call your shots, it makes troubleshooting more likely to reveal the source/s of error.

At 100 meters shooting an M855 load from a Service Rifle a 15 mph full value wind will displace the bullet about 1.5 inches. That's not enough displacement to need to counter, unless you are shooting at something like an MR-31 target. Not countering on that sort of target would cause you to loose a point as well as X count.

One more thing, shooting the 75 or 77 grain target bullets at SR is not an issue, I shoot em at 100, 200 and 300 yards with good results, as well as convenience. But, for 100 and 200 yard prone reduced course target events the lighter recoiling 52 and 53 grain target bullets have usually helped me get higher X counts than with the heavier bullets.

 

[Oneteam]

Re: Wind effect

My ballistic app says it is about a 0.8 moa shift with a full 6 mph cross wind. Angle of the wind makes a difference as does any gusts versus steady wind.

 

[*greenhorn*]

Re: Wind effect

at Full Value i look at about .9 moa with 55 FMJ running about 3221-3230 on my 308 its abot .5 mil 178 amax 2698 FPS but that's a constant, if varying i hold 1/2 mill and fire and the tail of the gust. 75-80% time works out in the "T" section, if not they still be down.