in terms of trajectory and performance?
Depends on what you are shooting. The .25 is a better varminter and the .27 is better for elk and larger. On deer-sized game there is a lot of overlap.
Seems the one and the other are interchangable.
Again, depends on what you are shooting. If I was going for elk I would take the .27 and a 150g bullet, for varminting the .25 and a 75g bullet.
How does the 257 WBY stack up against the 25 WSSM and the 270 WSM?
No interest in any of the three as my .257 Roberts with +P loads and my 7mm Rem Mag have that ground pretty well covered. But if I was choosing a new rifle in the .25 and .27 callibers, and couldn�t choose another Roberts, I�d stick with the .25-06 and .270 Win. No WBY, WSM or WSSM�s for me, thank you.
YMMV.
