Just looking at the Sierra Manual where the 7MM WSM and 7MM Rem mag are listed back to back. The 7MM WSM matches the velocities of the 7 MM Rem Mag until you get to the 175 grain bullet. Here the Remington mag pulls away with a 150 FPS advantage over the WSM. This because of the WSM's biggest weakness, heavy bullets have to be seated to deep to function and this takes away the powder capacity needed to push the heavy bullets to their max. Without some new powders, the short mags will never be able to match the long version when you get into the heavier bullets. As said above, thats physics. This holds true for all the WSM's but for some reason, the 7MM WSM as stated in many of the manuals, seems to suffer this the most. For this and other reasons, I don't see the 7MM WSM surviving in the long run.