I shot a 300 WSM for years. In the field, there's no practical difference between it and the 300 Mag. Last year I switched to a 30-06 to save a pound in weight. After shooting a bunch of elk with the 300 WSM, I can't think of a single one that I couldn't have shot just as well with a 30-06. The 300 Mag might get you 200 fps more than the 30-06 but unless you're shooting very long range, the difference is negligible. If you like, you can also shoot 165 gr bullets in the 30-06 for a good gain over a 270 and have plenty of power for elk.
