The reason I like the Weatherby's is the the double radius shoulder. That design really improves case life over other belted mags. Yes the 6.5-300 is overbore but the velocity gain over the .264 Win. Mag. is about 300 to 400fps. There doesn't appear to be any loading data yet to let us know how much powder is being burnt. However everyone would grab it if it were a 270 cal and a 130 grain bullet at that velocity. Which really this is very close to with a betterB.C. bullet.