6.5 creedmore has never been close to the best selling rifle cartridge let alone best selling over all cartridge. It’s just been an upcoming round in the past few years.

if we were discussing 300 yards max... the .308 is going to have negligible drop or drift compared to the 6.5 but it’s going to have more energy... the 6.5C doesn’t start to takeover the .308 until outside of 500 yards and even then the .308 retains a small advantage in energy.