Mr. T (MrT4) said:

Actually I am a bit surprised that 6.5 Creedmoor was chosen over .260 Rem , a design that is far better suited for automatic weapons and also has a bit more boiler room and can push bullets to higher speeds

6.5C was chosen as it had more Ogive space for use with heavier weight projectiles / experimental future projectiles:

https://soldiersystems.net/2018/03/23/ussocom-adopts-6-5-cm/

That's fitting considering neckless looks more and more viable (even brass case because of our man emeric) so of course we'd pick one with more ogive space right as more ogive space stops being a problem.

Yup, that sounds about right...

I cannot even at this point.