Wow, this is one of the best discussions I have seen on here in a while. So, here is my input:
.223 REM........great gun out to 600 meters, but light bullet weight is subject to wind
past 300 meters
.243 WIN.......shoots well, and inexpensive to shoot...accurate...my 17 year old
daughter shoots a Rem 700 SPS Varmint in competition and shoots 2 MOA
at 300 yds on 20 round group; light recoil
.270 WIN.......really flat trajectory...no issues at all at 300 yds...my Dad has a HOWA and
it shoots great, but kicks the fire out of you
.308 WIN.......great all-around choice...shoots anything from 110 grain up to 200 grain
bullets; very accurate and a good choice from 100 yds out to how far can
you see; not as flat shooting as .270 but less recoil and more versatile
.30-06 SPFLD..proven weapon capable of .308 performance and better, but recoil is more;
costs more to shoot and provides no better accuracy than any other caliber
Other 6mm and 6.5mm calibers are super target rifles, but generally costs a good bit more to purchase one worth having, and are likely better at punching paper than anything else. If that's all you want to do, then they are great. If you wish to hunt, then I would stick with one of your original calibers.
Given that undeniable logic, is there any way to determine a sort of break-over point? That is, at what point does a heavier, slower bullet with a high BC get blown off course more than a faster, lower BC bullet that is affected more per unit of time by the wind but has the advantage of being affected for less time due to its higher velocity?
I don't have a definitive, scientific answer to the above question; however, I will give you an example from my high school football days. There was this fellow up in TN from Lake County...he was about 300 pounds. I don't quite know his BC, but his sectional density was high, and once he got up a head of steam, it didn't matter who ran into him or at what angle or velocity, he didn't veer off his course much until he got where he intended to go. It is the same with heavier bullets. If you do the ballistics on a .308 Win at varying weights and velocities, you will find that the smaller bullets are touchy as stated in a previous post, and the really heavy bullets tend to be a bit on the slow side and drop too much. But like most things in life, if you pick something in the middle, you will find that it performs much better than either extreme. That is where the .308 falls out, somewhere in the middle, and in the middle of the .308 spectrum, something in the 155-180 grain range seems to perform best between 300 yds and 1000 yds. For 300 yds, I have found the 165-168 grn bullets do well, and past that I prefer the 175 grn.
Whatever you choose, they will all get the job done. Each caliber has it own advantages and disadvantages.
If you want to do some ballistic analysis for free, use this on line software. I have found it to be accurate.
http://www.biggameinfo.com/BalCalc.aspx