You've never heard of .260 Remington before? Yeah, it's what should have been the 6.5 CM, but Remington's marketing team royally fucked up everything by giving up supporting the round WAY too soon, and it almost killed it completely, if it weren't for other brands and aftermarket brass companies making brass and dies for it.
The .260 Rem debuted in 1997 (the 6.5CM was released in 2007...10 years later), and it was almost DOA, because it was pretty much flopped by the year 2000, thanks to Remington's shitty marketing team. That said, if I remember correctly, the 6.5 Creed was a bit of a slow-burn at first, too... It didn't start getting really popular until about 2010...So, it took a few years to really gain some heavy traction, and you see how much it's soared since then. Had Remington just kept goin with the .260 Rem instead of basically killing all support and marketing for the round, it might have been where the 6.5CM is today, and the 6.5CM might not even exist.
I've always loved the .260 Rem, and still have one. It's a great round, especially with a modern 1:8 twist like the 6.5CM standardized for 6.5mm bores. And if you blow it out into a .260 Ackley Improved 40º it's a very badass round.
That said, I'm very much enjoying the efficiency and ridiculously low recoil of my custom 20" 7.5" twist Proof Research barreled .25 Creedmoor with the Berger 133 Elite Hunters. Video of it using my OCL Hydrogen-S 6.5mm can coming up in the next week or 2.