Yes that will get your attention as well as testing your scope mounts😁
My 375 Wby is braked and is a pleasure to shoot. With cast powder coated bullets Blue Dot is my go to powder.
For standard calibers 0.020” is my starting point. Weatherby cartridges start at mag length. When loading Barnes I follow their listed COAL for starters. Then there is the single feeding which a lot of my rifles are done by.
I’ve seen some spectacular damage from .30cal BTs on deer 100yds and in. One would think at 300 yds that bullet would have a more controlled expansion.
Moving to an Accubond should solve the problem.
Some brands of dies have a VLD seating stem as an option. You may find the bullet tip is bottoming out in the stem giving you a variant in measurement. This is where a VLD stem will help.