Why a creedmore? Ballistically, off modern actions, the .260, 6.5x55, and newby creed are within 50fps over any given load; I.E. identical. Ammo is readily available for all as well. The Swede has the hands-down advantage on hand loads, though. Being a long action, any bullet weight offered in .264 Cal can be loaded to any seat depth and still clear magazine wells; 160gr Sierra included.
As for rifles... I have a Rem 700 Classic, CZ 550 American, and a Tikka T3 L/H action Lilja barreled all in Swede. The Remington shoots Berger 140 hunters, Tikka Sierra 140 GK's both are half MOA shooters on 200yd zeros. Both ring 12" steel at 1000yds. I'm still looking for a 140gr load the CZ likes, HDY ELD-X is my next bullet to try in it. The Bergers and Sierra's would only get near 1.5MOA@200 trying seat depth variances and 5 powders charge weights ladder narrowed for nodal accuracy then 5 shot groupings at node charges.
I counted in Cabela less than a week ago.
20 different ammo the 6.5 CM
3 for the 260 rem
1 for the Swede
All the Walmart's Carry 6.5 cm ammo
You aren't going to walk into any store and always find ammo for the other 2.