I've read about people rechambering 7.65x53 Argentine Mausers with a .30-06 reamer, then using a .311 expander when reloading their '06 brass. I guess you'd call it a .303-06 or a 7.7-06.
The interesting thing about that conversion was that you didn't have to cut, swage, and fireform .30-06 brass into 7.65, like I used to have to do for my Argie. Just use ordinary '06 brass and a .311 expander.
My own ".311 Whisper" wildcat is nothing more than a .300 Whisper expanded to .311, just because almost all my rifles and some pistols use that size, and I have several spare barrels around in that size too. I don't expect any difference in ballistics, just convenience for my own personal situation.