Either one is good . The .260 is a .308 necked down to .264 (6.5mm) and the 7-08 is a 308 necked down to .284(7mm). There are slight neck shoulder diffrences to prevent interchangability for saftey but ballistically they are the same. Handloaders have a great selection of bullets in either caliburs. Choose the gun first and if it comes in either cal fine. I lean towards the .260 as It can be loaded down for small varmints slightly better than the 7mm-08 IMHO