What was said before is very true. What shoots good in one gun very possibly will not shoot as well in a different gun. With that out of the way, the load I worked up many years ago for my old 725 Rem. is 53 gr.IMR 4350 powder, i39 gr. Hornady SP, 9 1/2 Rem. primers. Not a full-power load, but one that shoots excellent in MY gun, and just flat smashes whitetail.
The .280 Rem. is a superb cartridge, good for most N.A. game, with the possible exception of the largest bears. Even then, it does not lack far behind the 7mm Rem. Mag. Good choice, in my mind.
With all that said, I gotta tell you my go-to deer rifle has become the 7-08 Rem., and I'm not figuring on switching again any time soon........