The wind-drift advantage at short to medium range is certainly there, but it is negligible until you start getting around 300 yds or more when you are comparing it to medium weight bullets with good b.c.'s for their weight e.g. around .5. You have more recoil as you are using bullets approaching 180 grains, meaning not much difference to the .30-06 with 180's. That is why the .270 was considered an advantage, milder recoil and flatter trajectory with 130's than the .30-06 with 180 grain projectiles. Also, the heavy bullets drop more over that short to medium range. Sure that can be easily calculated and allowed for, but it is much easier to hold right on the vital zone in field conditions without making the allowance especially if the game is running or with an imperfect rest or off-hand. You really only need a few of options with the high b.c. bullets, too many options and sometimes the one you want isn't going to be readily available.
You don’t need a bullet approaching 180 gr to get a meaningful increase in BC over the mid-weight bullets in .277” with BC of ~0.5. For example, the 6.5 CM 147 gr ELD-M factory load has G1 BC of 0.697 and ~10% less wind drift than the .270 Win 145 gr ELD-X factory load at 300 meters. Said 147 gr load can easily be zeroed for MPBR of over 300 meters, and has even milder recoil than the .270 Win. To be clear, both cartridges obviously work great for 300 yard shots. We’re just discussing slight but real advantages one way or the other. When you get past 300 meters, as can occur quite often in the open terrain of the West, the advantage becomes greater.
Sometimes the bullet you want isn’t readily available, regardless of how many high-BC options exist in the caliber in question. More alternatives means a better chance of finding another option that shoots well in your rifle, and is available.
