Actually, not totally so DG. The bullet can become unstable in flight due to lack of spin. Also, the BC's of alot of bullets are not that high and will become even more unstable, hence the reason for .308 and heavy bullets with BC's greater than .5 or so.

I think what you are asking is effective range without using mildot or bullistic plex scopes or guessing how much to shoot over an animal to hit your mark without the bullet travel being +/-3" or so from zero. +/-3" is my comfort zone anyway. If you sight in a .270Win at 250 yards with an 130gr spitzer with BC of .436 at 3060fps velocity, that would be the max you would probably want to, to get effect sighting on your game. In other words, the bullet wouldn't rise up more than ~3" over your zero up to 250 yards and would drop 3.5" at 300 yards with a velocity of around 2400fps. So I wouldn't feel confident in taking the shot past there where you had to guess on a deer sized animal. So IN MY OPINION. 300 yards would be your limit of this round without target turrets or something like that. Only thing a WSM will do is give you maybe another 250fps or about .5" difference in drop at 300 yards. So your drop at 300 yards would be 3.0" if sighted in at 250 yards.

You might be able to sight in at 300 yards but the bullet would elevate to 4.1" at 150 yards and I wouldn't feel comfortable shooting a deer at 150 yards knowing I could be 4.1" high worse case. Still only buys you 50 yards. And doesn't buy you much with wind drift either. The WSM would buy you .5" in difference of wind drift at 300 yards with 10mph wind at 90degree angle.

Saying all that, I still like the 270WSM and WSM family. All my shooting buddies have had great luck out it and even exceeding the .300Win Mag velocities. I think the fat cases are a good idea for accuracy also. So I would shoot either one at a deer or even an elk.