My T3 270WSM's will shoot under 1" groups with factory Winchester Supreme 140gr Accubonds. I reload for both, my wife just prefers the factory...dont ask me why.
This is what I would recommend, and maybe the WS Elite 150gr XP3's.
next would be Federal inthe 140gr AB's.
As mentioned, bBuy a few boxes and see what shoots best in your rifle....everyone's may be different. I know when a buddy of mine bought a T3 270WSM in the camo model, shot my reloads initially to sight in...my reloads shot just as good out of his as it did out of mine. He used the factory WS 140gr AB's. If he had no ammo, Ican help him out.
And actually I picked up a T3ss 270WSM for a buddy off a fellow memeber here couple months ago for a good price. He will be using the WS 140gr Accubonds also.