I do not own a 300 WM and have only put a handful of bullets through one. But, if I were to build one I would shoot the 215 Berger Hybrid and put a CIP length DBM on it.
I started shooting Bergers a few years back just on a whim. Killed three elk with three shots that year and never looked back!
They shoot great, hit like the hammer of Thor, and seem to me to be pretty easy to load for in all of my rifles and all that I've loaded for. Especially in a rifle that is throated properly (small jumps).
Since then I built my first custom, it was a wildcat I designed. In researching that I noticed that for whatever reason if you take a cartridge that is not extremely over bore (and less is more here), and seat the bullet to where only the boat-tail (or less) is below the neck. That cartridge will have a hard time NOT shooting.
Examples: 6mm BR, 30 BR, 7mm GT, 6.5 SS, 300 WSM
(on a long action), 300 WM (seated long), and I'm sure there are plenty of others I'm not thinking of right now.
So, as I said, start with the 215 hybrids, H-1000, and a CIP length magazine that will allow you to seat the bullets out that far. And I think that you will be pretty happy.
I'm just a self taught red-neck that can't get enough trigger time so take all this with a grain of salt!