I can come up with four differences without thinking too hard:
1. Lots of cataloged firearms chambered in 6.5 Creedmoor compared to very few firearms cataloged in 260.
2. Lots of commercial ammunition options offered in 6.5 Creedmoor compared to few commercial ammunition options offered in 260.
3. 6.5 Creedmoor commercial ammunition widely available at high volume retailers like Wal-Mart compared to none in 260.
4. The shorter 6.5 Creedmoor case allows for longer VLD style bullets to fit in a 2.85" magazine box better than they do when loaded in the 260 case. When you're loading longer VLD style bullets there needs to be a balance between case length, bullet length, and magazine length.
Or so it seems to me, a guy with 25 260s.
