The NRAs explanation of why the 6.5Creedmoor is better than .260............

I disagree, unless you start reaming them. The whole point is to be able to seat the entire bullet in the neck above the neck-shoulder junction where the donut forms. If your brass is like 243 with long sloping shoulders, that junction is further from the case head. Seat the bullet above that point, and you have an OAL that exceeds what a standard AI mag can handle, right?
If you do that with a cartridge like the 6.5 creedmoor, you still couldn’t fit it in most magazines and would have to chamber the action with a longer throat than saami to begin with or the bolt wouldn’t close.
 
One thing I'd love to see now that Ted has an AW mag optimized action is an ARC AW style mag. I love AW mags, and for all intents and purposes, they're perfect. The only downside is the welded floor plate, so unlike AICS mags, I cant add a mag extension for those pesky 12rnd stages.

If you do that with a cartridge like the 6.5 creedmoor, you still couldn’t fit it in most magazines and would have to chamber the action with a longer throat than saami to begin with.
Both the .243 and the .260 have plenty of room in a mag for the higher BC heavies.

.260 in an AW mag. Plenty of room.

1675904891196.jpeg