The only thing close between a .270 and a .300 at 400 yds or more is velocity, and the .300 is throwing a heavier bullet to boot.
The energy isn't even close if you want to consider that. Probably 600 fpe more for the .300 WM at 400-500 yds.
If you're going to do your shooting at 100-200-300 yds., the .270 is fine but I wouldn't favorably compare it to a .300 WM at 400 yds. and beyond.
There is little difference in recoil between the .270 and .30-06 and little difference between the .30-06 and .300 Mag.. When hunting you'd have a tough time feeling the difference.
Those comments made above about the Weatherby Mag are really over the top.
