I was wondering about how much affect wind has on bullets. does anyone know approx how much a 10mph cross wind would effect a 45grain 223 bullet traveling at say around 3500fps. How much would this effect the bullets impact at say 100yards.

Cowboy, most load manuals have this info in their trajectory table section or near there anyway. I cannot answer your question without knowing the BC of your bullet. Contrary to what many think, it isn't drift, it's deflection, and the magnitude of it is primarily influenced by drag coefficients or BC.

The formula is D=W(T-Tv) where:
D-deflection
W-crossrange wind velocity in fps.
T-Time of Flight
Tv-Time of flight to same distance in a vacuum

You can likely find the "T" in a number of load manuals as well. FWIW, the data you find will be developed as if in a sterile lab environment, all winds steady, and so forth. It isn't the way of wind however so take it with a grain of salt. What may surprise you is that if you calculate the issue as "Drift", or TOF x Wind Velocity, you will find out just how much bullets don't "Drift". Lateral movement of bullets as a result of wind deflection is always less than the time/distance calculation by quite a bit.

"Drift" data from Hornady for their .224 45 gr Hornet bullet(BC .202) at 3500 fps, 10 mph crossrange velocity, 1.3"@100 yds, 5.4"@200 yds., and 13.2"@300 yds. This may not be what you're looking for but it illustrates that the deflection is not linear, ie., double the range and you get more than 4 times the lateral movement in the 2nd 100 yards of bullet flight in this example.

Hope this helps.

Yes, if your bullet has a BC of .210, which is possible for a 45-grain .224" spitzer, a 10 MPH, 90 degree crosswind will cause it to drift 1.66" @ 100 yards, 5.58" @ 200, 12.83" @ 300, 24.31" @ 400 and 41.24" @ 500 yards. Bullets with lower ballistic coefficients will drift proportionately more than this.

That is a considerable amount of drift over a faily short distance. I was shooting winchester white box 223 and black hills with 52 grain smk out of my handi rifle this weekend, there where off an on wind gusts, the gun for the most part grouped pretty well. but some groups POI seemed to move a bit, the trigger on these does take some getting used to.

Here is a trick an old friend told me to try; it seems to work. If you want to shoot on a windy day and you want to be evauating your loads and not the wind, shoot your loads at 50 yards instead of 100. The effect of cross winds will be 1/4 that of 100 yards. To keep group data consistent, extrapolate (double) the group size to show what it would be at 100 yards. The end result is that the wind effect at 100 yards is now 1/2 of what it would have been if the shots were acturally taken at 100 yards.
Ron

The only sensible explaination of wind drift that I have ever read is in Vaughn's "Rifle Acccuracy Facts".
It is not the wind blowing against the side of the bullet (drift would be a function of time of flight).
The spinning bullet aligns itself so, that the flow of air is head on (zero angle of attact). Now the drag
is not aligned with the path of flight. It is the drag component that points down wind that causes drift.
As BC is defined in terms of velocity loss the drift is a function of velocity loss.
I think this is the best "Gun Book" ever written.
Take Care!