.260 Rem or 6.5 Creedmore?

[Tumbleweed]

Hey guys. Going to build a first long range deer rifle and short range elk rifle for the kids. I think I'm down to these two cartridges. From the research that I've done the ballistics are virtually the same. I will however be running the 140 bergers and want to be able to fit the cartridges in the mag. Not sure if I'll need to actually seat the bullets to the rifling but if I do, in a .260 is there sufficient room in the mag for a long seated 140? This would obviously be a short action chamber for a .308. Thanks