I've got a RSI in 7x57... and love it.
The 7x57 in a strong action like a Ruger #1 International (full Mannlicher stock) is, to me, "THE" perfect combination of a classic rifle in a classic caliber. The only thing that might make it a tad more "classic" would be if it were in a 7x57R (rimmed case)... but the rimmed cases are harder to come by than the standard 7x57mm cases and I handload... so that's an important point.
Since the #1 action is so strong, the 7x57mm Mauser cartridge can be loaded to higher (50,000 CUP) pressures than the standard factory rounds which are loaded to the SAAMI maximum pressure of 46,000 CUP due to the older, weaker 1893 and 1895 Mausers still in use around the world.
When the 7x57mm Mauser cartridge is loaded to it's full "capacity", it slightly out-classes the much newer 7mm-08 Winchester round which has been gaining popularity for several years.
Isn't it strange that a cartridge that was introduced almost 120 years ago can still very much rival and even exceed one of the newest cartridges that has been brought out and gained so much popularity?
As for the RSI in .270 Win. that was sent to you in error, I won't get involved in the on-going, old argument about the .30/06 Springfield vs. the .270 Winchester... they are BOTH excellent hunting cartridges.
Strength & Honor...
Ron T.