The 270 wby is a good cartridge for longer shots. I have been working with the 250 SST's out of one of mine at 3300 fps. A .525 at 3300 fps is a very good long range round. My 7mm wby though has better numbers and so does my 264 STW. Not saying the 270 is not good because it is. Just the higher BC 7mms give that caliber better numbers at long range. I have made some amazing shots with my 270 wby and love to shoot it. My longest kill with it was an elk in Colorado during the 1970's at about 1100 yards.
There's the proof in capable hands. Here are some things to ponder also.
There are two things to consider when picking a bullet... BC and velocity. If you are shooting a high BC bullet for caliber, you want that to help negate the effects of the loss of velocity. The high BC then comes into play in maintaining energy.
Now to stir some feathers. The optimum velocity for most bullets is right around 1800fps. This is optimal for the bullet to open up correctly and do what it is designed to do. So with that said, if we look at say a .224 caliber bullet, 1800fps is way out there, but energy is low. This in theory means that the bullet should open up and act as it should, but does not have the down range energy, but you have a functional bullet due to velocity working as the catalyst. Soooo... the 270WSM has been disproving the theory of BC is superior.
BC is definitely a factor in producing proof positive results of creating good wound channels and maintaining its ballistic superiority down range in the wind. But we have calibers like the 25-06 and 270WSM that can smoke low BC bullets down range that perform as they are expected because of velocity. 600 to 700yrds is not difficult for a 270WSM to smoke deer size game at that distance. Good shot placement on an elk I would imagine do what it is suppose too.
If you were to use the 150 SST at a velocity of 3200+ you have enough energy to knock down an elk to 610yrds (2123fps, 1501 energy) and deer/antelope to 880yrds (1745fps, 1014 energy). If we stay with the theory of 1800fps, theoretically we should be able to harvest an elk due to proper bullet function at 840 yards. You just would not have the energy to punch a bullet through the animal (in theory).
Condition for calculations:
950ft, 30 deg., 29.69 Baro, 46%Humidity (Today in PA)
So if you were hunting in elevations of approximately 3000 to 5000 feet you would have enough energy to take an elk at 700+yards with a 150grn Hornady SST or any bullet with the same design and comparable BC.