Re: Dont\' often see the .270 mentioned
We are after accuracy as a rule so an accurate 270 would be a good choice. I can't really explain the lack of 270's currently in the LR arena.
For a strict comparison, the numbers you offer would certainly push some folks to the 270 over the 308 Win. I guess it's just the Match Shooters vs the Hunters that keep the 270 on the low end of use for the LR crowd... I have no real explanation that can be anything other than the 270 was just not popular at the time things got started.
The numbers you post are (just from memory and my thumb rule) a very near match for comparing a 308 Win to a 300 Win mag (~2/3's the drop of a 308 Win for the 300 Win Mag). This puts the 270 in the class of the mid-flat shooters, a good choice as a step up from the 308 Win (as I elect to see chambering choices). BC's drive the show as a rule once I'm beyond 500 yards, inside 500 yards even a red brick is sufficient for a good (reasonable) trajectory. It looks like the 270 would give a hunter (1000 ft/lb rule hunter to which I don't subscribe) about a 100 yard edge/extended range.
Just as an additional comparison, if you don't mind, run a 308 Win with a 175 Sierra (.507 BC at 2650fps), a 270 Win with a 150 SST (.525 BC at 2900fps), a 300 Win mag with a 190 SMK (.525 BC at 2940fps). Perhaps 500, 700 and 1000 yards.