6.5/06 with 140gr Bergers. With a light palma contour it won't be a flyweight so go long action for the case capacity. 260 AI can get close but you'll need a centerfeed mag/bottom metal for it to feed reliably, so an ADL long action will wind up lighter.
He wanted a short action caliber, I dont think an 06 based case fits into a short action.
