Re: new guy here
The 260 is basically a 308 necked down to 6.5mm or 6.5-08.
Its advantages over the 308 are all down to the bullets.
6.5mm bullets are regarded as the most accurate medium to long range ( up to 1000yds ) bullets you can get.
Because it can be loaded with lighter bullets, these bullets can be launched faster and because these lighter bullets have similar or even better BC then the heavier 308 bullets, you end up with a bullet that is faster, will reach out further and is better in the accuracy stakes then the 308.
The barrel life should be comparable with the parent simply because you are not forcing alot of hot burning gases through a small hole and thus eroding the chamber throat.