Rosharb,
I use 180 or 150 grain .311 or .312 diameter .303 bullets. .30 Caliber bullets are too small and will not give adequate accuracy in most .303 caliber rifles.
For most .303's you have to full length resize the cases with each loading the exceptions are the P14 Enfields with front locking lugs etc. And you will have to trim the cases to the correct length more often due to case stretching in a rear locking action.