hd12b,
As Curt said, a 4000 grit mild ball will also help cut down over/under reaction. I still don't believe the 300C is that ball, ESPECIALLY for someone whose ball speed is 12 - 13 mph (Assuming that Qubica, which measures at the backend. Heck, my ball speed is sometimes as low as 13, but usually 14 on QUbica machines and I know I can't use the 300C.
If the Natural is working, a pearl, like the Natural Pearl or the Avalanche Pearl urethane might be an even better choice.
Mild solids like the Motiv RX-1 orange and the Visionary Blue/Green Centaur might be excellent choices. I know Scotts33 and I both have used the B/G Centaur for years to cut down on over/under reactions on mild wet/drys at anwhyere from 2000 to 4000 grit.
Scotts33's suggestion to cut down on your rotation and use more end over end release is of major importance on wet dry conditions..
"None are so blind as those who will not see." "Some bowlers are crazy as pickled cats."