The 7.5x55 is a superb cartridge. Shorter than the 30-06, longer than the .308 Winchester and fatter than both. Ballisics are closer to the 30-06.
Brass is also made by Privi or it can easily be made from .284 Winchester simply by running the .284 case into a 7.5x55 sizing die.
In the Swiss K31 military rifle, this round is damn near unbeatable in vintage military rifle matches here in the states.