The 7 WSM does nothing over the standard 7 RM.
They are pretty much identical in performance with the same length barrel. You just get a little shorter overall package with the 7 WSM. It still burns as much powder, kicks just the same, just in a shorter/fatter case with no belt. More of a personal preference IMO.
Not knocking the cartridge as I've owned them both, but I still have the 7 RM. It'll push a 162g AMAX at 3100fps with a hefty dose of Retumbo or H1000 from my 24" bbl. It also shoots the 168g and 180g Berger VLD's at 3000fps and 2850fps.
Theres nothing wrong with either the 270 WSM or a 280 AI. Properly loaded, either will kill deer or elk a ways out there.
