I have always wondered about one thing when firing into a cross wind, So lets say I fire a round at a target into a 20mph cross wind at 2500fps depending on the weight and BC it will deviate a certain amount. What if I send the same bullet at 3500fps will the deviate the same amount, and then what if I send it 4500fps still the same amount? that makes no sense certainly a bullet "Charging the wind" will be less afected than "Sailing along" my take is something that spends less time in the wind will be less affected by the wind. the time of flight is so short how could it possibly, I have never taken into acount a cross wind when firing at a target and there never been a shot where I though, "I should have added some windage" so there has to be something to that since I rarely send anything less than 4000fps. Mind you this all happen's at less than 400yrd.
Dean
At less than 400 yards, it absolutely makes more sense to go lighter and faster. This concept actually occurred and was demonstrated to me when I was a little kid, and it went like this....
I played around with a wrist rocket a ton, and I would shoot whatever I picked up off the ground or could find laying around, and I would often grab a pocket full of dog food and shoot the kibbles at stuff, it was plentiful and worked. We had an old beat up aluminum shed that I painted a small dot on for target practice, made a loud bang when you hit it that I loved! Shooting the dog food at it was cool, at about 10 yards it was flying super fast, would almost always smack where I was aiming, and would then shatter into a bunch of pieces. The dog food was awesome for shooting at grasshoppers and stuff like that I could get close to, and wouldn't damage the skirting around our mobile home (where the grasshoppers would often hang out). But shooting at that same dot at 20, 30, or especially 40+ yards, the dog food was almost useless if there was much wind. So if I was shooting farther than 10 yards or so, I had rocks in my other pocket pretty close to the same size. I had to be more careful what I shot rocks at as they would do more damage and retain energy better, and wind did very little to them. They were reserved for the elusive english sparrows and starlings, in locations that had a safe backstop or just pasture behind them. I probably lobbed hundreds of rocks at those birds, and eventually I did get one English sparrow, but it was mostly futile attempts.
Though this is a slightly exaggerated example, it tought me something that applied directly to rifles, but was just scaled up a lot. In general*, Inside 500ish yards, there is really not anything ballistically to gain from a heavy slower bullet. Wind drift will not be noticeably different, energy will be more than sufficient for either, and the light bullet will have less drop. But if past 500-600 and out to over 1000 is where you generally live, the heavier higher bc bullets will outperform. At those ranges, you will have to adjust elevation for even the lightest and fastest bullets anyway, what is a few more clicks? And the real challenger, the windage, is where you will see less adjustment or hold off needed for the heavier high bc bullets. And also, very often I see the heavier bullets catch the lighter ones in speed, taking away any advantage they might have had. It might not be until 1000 yards or farther, but people do shoot that far, and any advantage at those ranges are welcome.
Bottom line, I step back and look at what a rifle will be used for. My brush, sub 400 usually guns use light fast bullets. My long guns do not. Would you put racing slicks on your 4wd hunting truck? Would you but gnarly mt's on your Shelby mustang? One answer is not correct for all, so use what works for your situation and stack that protein!!
Sorry for the novel, I had nothing better to do ha ha!