The WSM series are all faster that the standard cartridges. The Short, fat case of all the WSM's is more efficient when it comes to powder burning. Look at the bench rest guys and what they shoot (22BR, 22 and 6mm PPC's, ect). The long, skinny powder collum is hard to ignite evenly. I sound like a ad...sorry. I should add, I don't currently own a WSM of any type, but that will hopefully change soon. On paper, they look good. I have to admit, the 300 win mag and the 300WSM are not much slower than my 300 rem, but the rem burns about 25% more powder. I'm shooting close to 100 grains of H1000 where I think the 300win mag is around 72 grains.
I digress... Seriously, go to riflebarrels.com (I don't know how to do a actual link) and look ant the articles on long range hunting. There's a shitload of info there and Dan Lilja makes one of the best barrels around. I have two of his barrels and they are by far my favorite barrels on my varmint guns.
Anyway...good shootin
Sleepy717