I would really like to do a 22-250 build, as I already have a bolt action 22-250 and wouldn't have to buy another caliber of ammo.
I know that 1biggun has mentioned the better performance and wider availability of ammo choices for the .260 Remington.
Then you have the interesting aspects of the 6.5 Grendel, being based on a 7.62x39 case with little to no taper.
I'm trying to decide on which one would make the most sense to build, given ammo availability, as well as potential magazine candidates, and what types and mods would need to be used for each round with respect to the mags. Whatcha think about the pros and cons of each?