Composition of Brass for Rustproofing in RP-SMA and SMA Antenna Cable Connectors

Typical composition of Brass n Antenna Cable Connectors, and what is the composition required for rustproofing?: I think that 70% copper content is higher than typical for antenna cable connectors. Please research what the typical composition of brass that is used in RP-SMA and SMA connectors and the bulkhead nuts and washers.