It all depends on what you want to do with it! 1000 yard BR Big .30’s rule the roost. 600 yard BR 6mm’s rule. F-Class anybody’s guess! I shoot a 6mm and I think that in 600 yard F-Class the 6mm will win on all but the windiest days. Anything, 6mm, 6.5mm or a 7mm will work well in the 600 yard game shooting for score. 1K F-Class I would lean towards the .300 WSM shooting the 210VLD either Berger or Sierra. Although the 187 BIB FB would be hard to beat. .300 WSM is the biggest thing that can be shot comfortably from a true 22# un-broke F-Class rig. It would not stand a chance day in and day out against the inherent accuracy of the 6mm’s.
Hunting! Give me a Big .30! Although an Improved 7mm WBY would work quite well. I like a .300 WM loaded with the 200 gr. ACCUBOND for my SR and LR Hunting rifle. Over a Ton of energy at 500 yards.
Bullet selection would be the determining factor!