OK! You tell me how it's logical to build a .308 length cartridge on a long action?
The .260 AI has an internal capacity of might near identical to the 6.5x55. Which means same/same velocities at the same/same pressures. If one is looking to increase velocity, then it stands to reason that one must increase capacity or increase pressure. (FWIW; a larger cartridge is the safer of the two...)
Assuming that one is using a long action, then it's logical to go with the 6.5/06, 6.5/06 AI (Or as I did, 6.5x64 Brenneke...) or .264 Win Mag. (Or a host of other wildcats for that matter...)
One can spend a lot of time, effort, and money trying to reinvent the 6.5x55, But in the final analysis, the 6.5x55 has been doing it's job with aplomb for more than 100 years.
I don't know about anyone else, but I always have to do the wrong thing 4 or 5 times before I know what the right things is. Like Jim Croce: "I learn the hard way every time..."
YMMV
