Physics does indicate that a larger ball will resist wind better than a smaller one but that is if the two are the same MV. A .40 doing 2,000+ fps MV isn't in the wind for long at 100 yds or less. But you still have to read wind, light and mirage with any of them.
I was thinking along these same lines, TC... Low to the ground, maximum 60 yards,,, unless it's a hurricane wind - I can't see a drastic wind effect and even at that, you still play the wind with all shooting activities.
You need to come to Cody WY. We usually only have 1 wind flag and an impossible to see change down range will move a 50 caliber ball an inch or more. But we shoot in conditions that would cause people in the east to call the match.
As are result we see things like this where it always just a little stronger than I think.
And this part of the same match (we were short of targets and shooting three on each that day)
When the wind does its 180 degree shift in direction and things start going off the other way.
Or at another match this sort of thing which includes my sighters for the day and I never could seem to catch up.
So its very common to have a string of shots strung across the target left to right. There are no sighters once we go for score.
These are three targets shot by three different shooters on the day of the "sighter" above. Note the similarities. One was a 45, the schuetzen target was a 40 IIRC. Mine is a 50. All targets are "sighter" targets left up and score targets put over them.
But we don't shoot off a chunk since we have shooters that won't lay down. We shoot a "plank rest" another traditional rest for Turkey and Beef matches from a painting of a shoot in the winter in NY state probably in the 1870s.
A 45 in the hands of someone who can really read the wind can be very competitive. But he still holds far more wind than I do with the 50. Though I suspect I am making more velocity than he. A 40 would be a long way from my first choice for this no matter how well it shot.
Wind drift is based on how much speed the projectile loses over its flight to the target. This is why modern high ballistic C , .600 or so, bullets drift so little. But the RB cannot be improved except by increasing its diameter.
In the 30 pound rifle I would go with a .662 or larger ball and a charge that shot well if wind was an issue. I know it will beat a 54-58 in wind drift. .662 is double the weight of a 530-535. But then it takes a lot of lead to shoot a match.
This is why people are shooting 50s and 54s with large charges of powder, wind, and its pretty well shown that heavy charges shoot better in many cases.
Dan