Midway shows 35 listings for the 300 WSM, 3 in stock, prices starting at $67 and up! I owned one, a custom barreled Win 70 FWT, it was nice, sold it to a guy on the CF many moons ago.
On the other hand, Midway lists 103 options for the 30-06 with 64 in stock with prices beginning at $25.
As much as I think the WSM is fine, the '06 is the easy button of 308 cal. if the "308" is not your fancy (I have both).
Also, 76/36/$29 for the 300 Win Mag
That's what I eventually decided, after owning quite a few .300 magnums, including the three WSMs mentioned, several .300 Winchesters and a couple of .300 Weatherbys. Plus, the .30-06 is pretty close to the .300 WSM with newer bullets and powders. My latest handload for my Ultra Light Arms .30-06 is the 175-grain Barnes LRX and the maximum charge of IMR4451 listed in Hodgdon's data for 175-grain bullets--which gets around 2850 fps. Plus, have taken big game out to around 500 yards with the ULA, sometimes with 180-grain factory loads, in North America, Europe and Africa.
But have also come to the conclusion that the major fault of the .30-06 it's too boring for many rifle loonies....
