.300 Weatherby or .340 Weatherby? Well, first off, the .340 will deliver as much as 400 fps more than the .300, but who cares. I would think that you would want to shoot for accuracy, not necessarily velocity. Based on that alone, I would choose the .300 WITH A BREAK; preferably one that does not dig a hole in the ground and Badger Ordnance manufactures a good one. The .338 Lapua was designed by the US Navy to be their SWS Caliber of choice and yes, it does do everything the .300 Win Mag. does, only better.