Performance wise, the .243 buried the .257 a couple of generations ago...
The loading manuals of the 1970s listed the Roberts in their "obsolete" section, if they mentioned it at all...
It was Bill Ruger, who excelled at accomodating riflemen's lust for more classic things, that was most responsible for resurrecting the BOB. A few writers here and there took delight in feeding that dog...
There is nothing that one will do that the other won't, for a hunter of game...
As to the "older" cartridge, they both have bones there now. In the 60s the .243 was still new-fangled, but that was a while back...
The .243 was my "go-to" cartridge for decades... I'd guess that Milek was most responsible for my quarter-bore conversion...
