it is more powerful than a 7 mm rem mag and more accurate.
My own chronograph has shown this to be total B.S.You have been reading too much winchester and browning advertising propaganda.The 7mm remmag has more case capacity and a larger bore and if both are loaded to potential the 7mmremmag will produce more velocity with the same bullet weight and therefore more energy making it more powerful.Even the 7mmwsm falls slightly short of the 7mmremmag in real life.I have chronographed the 270wsm and 7mmremmag myself both with 140gr bullets and the 7mmremmag did develop over 100fps more velocity.
As to the theoretical accuracy advantage that the wsm's supposedly hold,it is purely theoretical.The quality of the barrel,the bedding and the load are far more important than the cartridge where accuracy is concerned.A fellow came to our range and spouted the same nonsense about how his 300wsm was more accurate than the 300win mag and all other full length magnums.When I offered to put my 300ultramag up against his 300wsm for a three shot group he smirked about about it because he did not believe that the much heavier recoiling ,much longer cased 300 ultramag could compete with his short cased much milder recoiling 300wsm.He was quite proud of his group which did measure under 1" but the smirk disappeared after my sub .600" group.I offered to go again and he accepted and managed to shoot a group just over .750" but my second group measuring almost exactly 1/2" really discouraged him.I have also had the pleasure to outshot a few other 300wsm's and a couple of 270wsm's with both my 7mmstw's and 300ultramags and I must admit that I enjoy the looks on the faces of their owners who believed that any wsm is more accurate than any of the longer cased magnums.
Not that the wsm's aren't very good cartridges,because I do believe that they are.It's just that they don't live up to the misleading advertising used by winchester and browning to promote them.