There's a few things to keep in mind when comparing the 30's to the 6's in Score shooting.
1. To take advantage of the the .30's bullet diameter versus the 6's, you need to
execute the shot with a .30
exactly as you would have with the 6. Only
then can you capitalize on the increased bullet diameter...which is a bit incorrect because it's actually the
radius of the bullet that may be the advantage. Bench technique (table manners), gun handling and recoil management are a lot different with the 30's....they are less forgiving of improper follow through, etc.
2. The biggest advantage of the 30's. is their ability to stay in tune across an entire days shooting. If you follow the road map for tuning these .30's, that's what puts the pancakes on the table. No more getting lost with the tune up, no more ratcheting the powder measure up or down...you keep your head in the conditions and let the gun do the work.
Bullet diameter won't save you if you press the trigger at the wrong time!
Good shootin'

-Al