RE: advantages of the .260?
No, the 6.5x55 isn't a typical cartridge you would find at Walmart, but can be fouind at just about any mom and pop gun shop. Just like the 8x57 its underloaded by Rem and their ilk since they don't think its worth their time to make usable loads with it and to a greater degree they are right by doing so as more money can be made by chambering rifles in their own proprietary wondermagnum cartridges. I'm just waiting for Rem to come out with a 8mm short magnum or 8mm08 so I can vomit all over my own shoes.
Alcohol, Tobacco, and Firearms... who's bringing the chips?