Weatherby .308?? I thought it was a .300 Weatherby??
I figured a .308 Win has plenty of power, 300 Weatherby costs like hell and the amounts of powder required to get the last bit of oomph are definitely in the area of diminishing returns IMO. If I wanted a 300 mag I think the 300 Win Mag would do it.
When I worked at J.F.R., our lead crew chief, Austin Coil had one of those .30 Lazzeroni rifles. IIRC, the cartridge was a .404 Jeffery necked down to .30. The barrel life was only slightly over 2,500 rounds.