I have an Xbolt Hells Canyon Speed in 300 WSM. sorry to say I spent a small fortune (money and time) trying to find a load that will shoot. Tried all the factory brands and like you, didnt find anything that would consistently group. I handload, so I went through that whole process as well. I also had to up my reloading game significantly with a better scale and redding dies. I finally landed on 200 Gr ELD-X, w Nosler Brass, H4831SC, and 215GM primers. i also upgraded the trigger to a Timney as the stock trigger was factory set over 5lbs, and would not adjust below 4lbs....lawyers trigger spring I think.
I just brought home my 6x5 bull elk from the Northern BC Rockies that dropped at 745 yards, so some proof the gun will now shoot.
i would look at the trigger first because 5lbs isnt going to help w accuracy.