Certain very early production 303 Savages had a larger groove diameter [.311"]
However, the majority use the standard .308" bullet.
The factory loading was, as mentioned, a 190 grain RN bullet.
These bullets are in short supply, so you may have to use bullets designed for the 30-30.
The 170 grain is a good choice.
I would avoid bullets designed for higher velocity, since they may perform poorly
at the modest velocities of the 303 Savage.
If you are using a M99 Savage, [ see you are] there is no need to crimp, so no need to seat
the bullet to the cannelure.
Regards, Eagleye.