Overbore cartridges like the .240 Weatherby and .257 Weatherby just don't make much sense to me.
Maybe not as varminters but as medium game rifles they are terrific. Most guys will never hunt enough deer, sheep, or antelope to burn up a 240 or 257 barrel.
I have had my 257 for a number of years and it is more accurate now than ever. My 240 is a West German gun that had many years on it before I bought it and it too is still a top notch shooter.