I had one in 30-378, well still do is but with a new barrel, and stock. A couple of things I learned from it.
Check the aluminum bedding block. A short time into load development and mine looked like a neglected cold chisel.
Skim bed it. Had absolute fits with it giving first shot flyers and then grouping. Bedding solved this and the cold chisel problem nicely. If you are having problems with accuracy, this is where I would start before burning any more powder.
RL25 in fast fire mode with that much powder turned into some kind of indestructible cement that was the demise of my factory barrel. Better options for the 30-378 IMO are Retumbo and H50BMG.
After cranking hundreds of rounds through it, the extractor got worn and started messing up the case heads. When the rifle starts feeling like there is a "pop" when you close the bolt, it is time to change the extractor. They are $14 available from Weatherby and take 5 minutes to replace. I now have 2 spares.
Enough of the bad stuff:
200gr Accubonds shot extremely well in the factory barrel, better than anything else I tried, and I tried a bunch.
Factory barrel shot very well. Chamber was great. All my little lugs touch. The single best thing I like about it, and the reason I would buy another, Is its bolt face size.