Head diameter on the .303 Savage is .442.
Head diameter on the .30-30 family of cartridges is .422.
.02 is getting to the point where you don't really want to try it.
A better route is to head swage .30-40 Krag cases.
I stand corrected!
I know they are about the same power but, never having had either one (.30-30 or .303), I always assumed they were of similar general dimensions.
After looking up the pertinent data in my cartridge book, I see that .30-30 is .422, and .303 is .439, a difference of almost .02"