I'm gonna stick my neck out and say the .300Win can be worked into a more accurate rifle solely because of the long run the Weatherby cartridge makes before engaging the lands. BUT, I'll be the first to say that bullet jump is NOT the do-all, be-all, end-all of accuracy.
I have no hands on experience with a Weatherby however. I have owned 3 300Winnies over the years and they have all been gratifyingly accurate. All Model 700s and they would shoot 200gr Grand Slams, NP's, and 200gr Speer Hot Cores into 1"-1.25". That was with scopes on the order of 1.5x5's and 2x7's.
Again, this is not a knock against the Weatherbys but rather a boost for the .300Winnie.