What you get with the .270 WSM is about 150-200 fps more than you get with the standard cartridge. The velocity increase comes via a powder capacity that is 5 to 6 grains greater. In the older cartridge, you can reach 2,950 fps with a 150-grain bullet, which I consider the most useful weight, while in the .270 WSM you can reach 3,050. I found that the lighter bullet weights give a greater increase in velocities. With 130-grain bullets you can get 3,250 fps, which is really moving.