Filaman,
You were misinformed about the powder capacity of the .260 versus the 6.5 Creedmoor--which is common. Most people don't have a clue about the differences between the rounds in a short action, but still spout all sorts of BS about the 6.5 CM, even if they've never played with both rounds.
If you want to learn about the real reasons, there are plenty of sources for the information.
