I've used a bunch of powders in the .280, but if colder temperatures might be encountered prefer H4831, which works just as well as it does in the Winchester "imitation .280" they call the .270. With 140's I generally use around 60 grains, with 150's 58.5, and with 160's 57 grains. These aren't found in published loading data, which is pressure-limited due to pump and semiauto rifles, but they've worked fine in several bolt actions.
What this guy said.
