I would check all the screws (rings, bases, and action) to make sure they're tight. Did you take out the action screws and clean the oil off of them when you got the rifle and retorque them to the recommended torque?
When I received it as a bnib rifle, no I did not remove the action screws, clean them and retorque them, as I have done in the past I mounted the scope, bore sighted it and shot it using the only factory ammo I received 130gr Sciroccos,
I gave the rifle to my gunsmith and checked everything over, shot it with the same results with the brake on and off, when he got home from the range he borescoped the barrel and did find excessive fouling on one spot in the barrel, he also found a lot of forend pressure on the barrel when he retorqued the action screws to factory settings.
So I changed the scope, no difference in the grouping.
Put the Leupold back on tried the 127gr lrx and 3 handloads with different bullets same results, so as I mentioned earlier that's 3 different guys, 2 different scopes, and 5 different bullets, and still the same issues, we also backed the action screws off this last time at the range before shooing our last group just to see if it would change anything and no it didn't.
Luckily there is a certified Weatherby repair center in British Columbia so after I speak to someone at Weatherby Monday morning and get some direction we can go from there.