From 26" barreled guns the 300 WM edges out the 300WSM by a bit. If both guns are 24" tubes call it a tie, the 300 WM might shoot 180's 25-30 fps faster.
The WSM's advantage is that it gives you 98-99% of a 300 WM velocity in a 308 sized package with hot 30-06 recoil and better accuracy. Since the WSM will get almost the same speeds, but with 10-15% less powder recoil is noticeably less. It hits about 1/2 way between 30-06 and 300 WM in equal weight rifles.
I've had both, won't be going back to the WM.
