What does a 10-12 mph wind blowing from my back straight at 100 yd. target, do to groups. I was testing some loads in a 22-250, these same loads were shooting ok, for the most part,a few days ago without the wind. Today groups had spread out badly. I was shooting 52 BTHP. I was getting groups under an in. The groups spread out to 1 1/2 or more. I knew the wind would change things some, but I didn't think it would be that much. Thanks for replys! BA

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I may be from Arkansas, but I never voted for Bill Clinton!

Shooting into and with the wind is the better of the choices. If the wind was across the range, you would have been worse off.

My highly un-scientific, rule of thumb is that a wind such as you describe will open my groups about a half inch.

Doesn't seem to matter what caliber.

Just my observation from shooting where the wind always blows!

IF the wind is blowing in EXACTLY the same direction as the bullet is travelling, either straight downrange or straight uprange, it should have no effect at all on group SIZE. However, most winds do move across the bullet path to some degree. BUT, a wind travelling up or down range would have some, probably unmeasureable, and negligible, effect on the velocity lost by the bullet in travelling 100 yards.

In theory, a moderate wind exactly at your back should have no effect on groups. The rub is that wind, even over a range as short a 100 yards, is highly inconsistent. It may be blowing at your back at 12 mph at the bench, but be swirling at 15 mph half-way downrange at 45 or 60 degrees due to topography or obstruction.

There are few truly windless days in West Texas, where I do most of my shooting. But I have found phenomenal results, like 1.5" inch groups with a .222 at 400 yards, when one of those rare days comes along.

My experience is that wind, no matter the direction, is going to make some difference in your groups. A 52 grain .224 bullet will be more affected than a 180 grain .30.

a 10mph wind blowing straight towards you or from behind should have little or no effect at 100 yrds. Even a 90 Degree side wind will have little effect even if inconsistent( perhaps a 1/2 inch or so. At longer ranges however, there is a lift effect which will cause verticle stringing which can be severe in a gusting FTB orBTF wind. I've gotten nailed by that one before. Most likel,however, the wind may be swirling on you downrange and causing the groups to spread( thats why you need multiple windflags).-Rob

I never shoot without wind flags any more. I set one up about 10 feet in front of the bench, and another one about 10 yards in front of the targets. If nothing else, they explain those "flyers" better, and you'll become much more aware of your surroundings. I never realized that the wind could blow straight down, or be blowing in the complete opposite direction down range.
Regards, George.

Hey Bill, I'm going to guess your muzzle Velocity is around 3500-3700fps with 3600fps a workable probability.

And just for arguments sake, let's say you had a steady 10mph wind. Converting that, it comes out to be about 15fps or .4%(less than 1%) of the air moving around the bullet as it exits the muzzle.

Time of flight from your muzzle to the 100yd target is somewhere around 0.085-0.095sec, or less than 1/10 of a second.

So, the wind doesn't have much time or energy to expend on that 52gr bullet as it is zipping along to the 100yd target. For those folks convinced it has "totally destroyed" the grouping ability of the bullet - more power to them!

There have been MANY, MANY occasions where I'd loved to use that old wind excuse myself, but "IN MY CASE" groups opening at 100yds are generally attributable to "MY" concentration going into a slack mode.

Just last week I put 6-shots from a 223Rem into a group that appeared to be less than 0.3xx", or slightly less than 0.5" Outside-to-Outside. Went back to the Firing Line, concentration went away and the group really opened up.

It was sprinkling slightly, so I suppose I could "blame" the tight group on the rain drops "knocking" the bullets into the tight hole. And likewise, the lighter sprinkling caused the additional 7-shots (into the same group) to open it up. But, I really suspect my problem was simply a-lack-of concentration.

Sometimes it seems my groups are even affected by how much Iced Tea my internal reservoir is toting. Too much or too little and I can see the crosshair twitching erratically in the sand bags. Then have some yahoo mention Louise Mandrell and I might as well pack it up for the day.

Now, wind does indeed affect bullets, but in your specific example, my experience indicates it is probably something else opening the group. Any chance you were humming a Louise Mandrell tune as you shot??? ;^)

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Good hunting and clean 1-shot kills, Hot Core

I am afraid Louise Mandrell and lots of ice tea would have WAY more effect on groups, than any 10mph wind!!! Just thinking about Louise gives me a "mirage" effect. GREG

Well thanks alot Hot Core...I was really hoping you guys were going to tell me it was the wind, and not my crappy loads and or my shooting. Oh well, back to the reloading bench! Thanks for the replys, BA

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I may be from Arkansas, but I never voted for Bill Clinton!

Can't say about your 22/250 but I shoot a lot of 300gn cast bullets at about 1500fps in a 38/55 bull gun with 25x Lyman scope at 200 yards.

Wind from behind tends to cause the bullet to strike higher on the target. For 10-12mph from directly behind translates to about 1.25 inches at 200yds. Similarly a wind from the front tends to make the projectile strike lower by about 1.25 inches.

It is really amazing to be able to judge the point of impact at that distance by reading the wind flags. Left or right for cross winds and up or down for tail and head winds. Mind there are a lot of times that I get it wrong also.

In my 40/65 and 45/70 Sharps rifles I have struck another phenomen. Heavy lead 500gn + projectiles launched at around 1050fps do not appear to be affected very much by cross winds out to 600 yards. I've shot on days with 12-15mph winds blowing and when other competitors are adjusting their sights for windage I simply aim at the target and seem to get more hits.

I believe that because the bullet is starting out less that speed of sound, that it does not build up a pressure wall in front of the nose like high velocity pills do.

I should imaging that similar effects would apply to your problem