I've gone thru some components while working my 700 CDL up. I tried Varget, H380 and IMR 4350. Several different bullets, including the 139 Hornadays that have shot well in some of my other .284 guns. What I finally settled on was 48.0 gr. IMR 4350 with 140 gr. Accubonds. Shoots just around 1 MOA regularly. Somedays a little under, somedays a little over. You will find your OAL is limited in the Rem. magazine, and you probably will have to settle for what you can in that department.
Like Bronko said, different rifles generally have different appetites, and it will tell you what it likes best. The above-mentioned load runs thru my chrony about 2800 fps. Start below the 48.0 and work up to it. My manual lists it as a max load.